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Each phantom stock unit which represents a deferred stock unit is the economic equivalent of one share of Community Financial System, Inc. common stock and will be settled in common stock at a predetermined date."},{"field":"price","element":"transactionPricePerShare","label":"F1","text":"On April 29, 2026, the reporting person's phantom stock units were settled for 9 shares of Community Financial System, Inc. common stock, and .4418 shares were settled in cash at the price of $63.17 per share."},{"field":"derivative.exercise_date","element":"exerciseDate","label":"F5","text":"The reporting person has received deferred stock units under the Community Financial System, Inc. 2022 Long-Term Incentive Plan, as amended (the \"LTIP\"). Each phantom stock unit which represents a deferred stock unit is the economic equivalent of one share of Community Financial System, Inc. common stock and will be settled in common stock at a predetermined date."},{"field":"derivative.expiration_date","element":"expirationDate","label":"F5","text":"The reporting person has received deferred stock units under the Community Financial System, Inc. 2022 Long-Term Incentive Plan, as amended (the \"LTIP\"). Each phantom stock unit which represents a deferred stock unit is the economic equivalent of one share of Community Financial System, Inc. common stock and will be settled in common stock at a predetermined date."},{"field":"balance_after","element":"sharesOwnedFollowingTransaction","label":"F6","text":"Includes 9.4418 units of phantom stock acquired on April 10, 2026 under the LTIP's dividend reinvestment feature."}],"balance_after":1220,"derivative":{"underlying":"Common Stock","underlying_shares":9},"source":{"system":"sec-edgar","filing":"0000723188-26-000086","document":"form4.xml","document_sequence":1,"table":"derivative","row_type":"transaction","position":5,"url":"https://www.sec.gov/Archives/edgar/data/723188/000072318826000086/form4.xml","form_type":"4"}},{"id":796359,"issuer":{"id":4178,"kind":"organization","name":"COMMUNITY FINANCIAL SYSTEM, INC.","symbol":"CBU"},"owners":[{"id":50446,"kind":"person","name":"Parente John","position":1,"cik":"0001486057","reported_name":"Parente John","relationship":{"director":true}}],"security":"Common Stock","published_at":"2026-05-01T20:22:54.000Z","date":"2026-04-29","kind":"exercise","planned":false,"acquired":true,"shares":9,"ownership":{"direct":true},"footnotes":[{"field":"price","element":"transactionPricePerShare","label":"F1","text":"On April 29, 2026, the reporting person's phantom stock units were settled for 9 shares of Community Financial System, Inc. common stock, and .4418 shares were settled in cash at the price of $63.17 per share."}],"balance_after":72654.3212,"source":{"system":"sec-edgar","filing":"0000723188-26-000086","document":"form4.xml","document_sequence":1,"table":"nonDerivative","row_type":"transaction","position":1,"url":"https://www.sec.gov/Archives/edgar/data/723188/000072318826000086/form4.xml","form_type":"4"}},{"id":796358,"issuer":{"id":4178,"kind":"organization","name":"COMMUNITY FINANCIAL SYSTEM, INC.","symbol":"CBU"},"owners":[{"id":50445,"kind":"person","name":"Knauss Jeffery J","position":1,"cik":"0001900543","reported_name":"Knauss Jeffery J","relationship":{"director":true}}],"security":"Phantom Stock (Deferred Stock Units)","published_at":"2026-05-01T20:21:22.000Z","date":"2026-04-29","kind":"exercise","planned":false,"acquired":false,"shares":9,"ownership":{"direct":true},"footnotes":[{"field":"derivative.exercise_price","element":"conversionOrExercisePrice","label":"F2","text":"The reporting person has received deferred stock units under the Community Financial System, Inc. 2022 Long-Term Incentive Plan, as amended (the \"LTIP\"). Each phantom stock unit which represents a deferred stock unit is the economic equivalent of one share of Community Financial System, Inc. common stock and will be settled in common stock at a predetermined date."},{"field":"price","element":"transactionPricePerShare","label":"F1","text":"On April 29, 2026, the reporting person's phantom stock units were settled for 9 shares of Community Financial System, Inc. common stock, and .4418 shares were settled in cash at the price of $63.17 per share."},{"field":"derivative.exercise_date","element":"exerciseDate","label":"F2","text":"The reporting person has received deferred stock units under the Community Financial System, Inc. 2022 Long-Term Incentive Plan, as amended (the \"LTIP\"). Each phantom stock unit which represents a deferred stock unit is the economic equivalent of one share of Community Financial System, Inc. common stock and will be settled in common stock at a predetermined date."},{"field":"derivative.expiration_date","element":"expirationDate","label":"F2","text":"The reporting person has received deferred stock units under the Community Financial System, Inc. 2022 Long-Term Incentive Plan, as amended (the \"LTIP\"). Each phantom stock unit which represents a deferred stock unit is the economic equivalent of one share of Community Financial System, Inc. common stock and will be settled in common stock at a predetermined date."},{"field":"balance_after","element":"sharesOwnedFollowingTransaction","label":"F3","text":"Includes 9.4418 units of phantom stock acquired on April 10, 2026 under the LTIP's dividend reinvestment feature."}],"balance_after":1220,"derivative":{"underlying":"Common Stock","underlying_shares":9},"source":{"system":"sec-edgar","filing":"0000723188-26-000084","document":"form4.xml","document_sequence":1,"table":"derivative","row_type":"transaction","position":2,"url":"https://www.sec.gov/Archives/edgar/data/723188/000072318826000084/form4.xml","form_type":"4"}},{"id":796357,"issuer":{"id":4178,"kind":"organization","name":"COMMUNITY FINANCIAL SYSTEM, INC.","symbol":"CBU"},"owners":[{"id":50445,"kind":"person","name":"Knauss Jeffery J","position":1,"cik":"0001900543","reported_name":"Knauss Jeffery J","relationship":{"director":true}}],"security":"Common Stock","published_at":"2026-05-01T20:21:22.000Z","date":"2026-04-29","kind":"exercise","planned":false,"acquired":true,"shares":9,"ownership":{"direct":true},"footnotes":[{"field":"price","element":"transactionPricePerShare","label":"F1","text":"On April 29, 2026, the reporting person's phantom stock units were settled for 9 shares of Community Financial System, Inc. common stock, and .4418 shares were settled in cash at the price of $63.17 per share."}],"balance_after":4829.4908,"source":{"system":"sec-edgar","filing":"0000723188-26-000084","document":"form4.xml","document_sequence":1,"table":"nonDerivative","row_type":"transaction","position":1,"url":"https://www.sec.gov/Archives/edgar/data/723188/000072318826000084/form4.xml","form_type":"4"}},{"id":831626,"issuer":{"id":4178,"kind":"organization","name":"COMMUNITY FINANCIAL SYSTEM, INC.","symbol":"CBU"},"owners":[{"id":50447,"kind":"person","name":"Pecor Raymond C III","position":1,"cik":"0001475265","reported_name":"Pecor Raymond C III","relationship":{"director":true}}],"security":"Phantom Stock (Deferred Stock Units)","published_at":"2026-03-23T15:09:40.000Z","date":"2026-03-19","kind":"exercise","planned":false,"acquired":false,"shares":1254,"ownership":{"direct":true},"footnotes":[{"field":"derivative.exercise_price","element":"conversionOrExercisePrice","label":"F3","text":"The reporting person has received deferred stock units under the Community Financial System, Inc. 2022 Long-Term Incentive Plan, as amended (the \"LTIP\"). Each phantom stock unit which represents a deferred stock unit is the economic equivalent of one share of Community Financial System, Inc. common stock and will be settled in common stock at a predetermined date."},{"field":"price","element":"transactionPricePerShare","label":"F1","text":"On March 19, 2026, the reporting person's phantom stock units were settled for 1,254 shares of Community Financial System, Inc. common stock, and .5514 shares were settled in cash at the price of $55.61 per share."},{"field":"derivative.exercise_date","element":"exerciseDate","label":"F3","text":"The reporting person has received deferred stock units under the Community Financial System, Inc. 2022 Long-Term Incentive Plan, as amended (the \"LTIP\"). Each phantom stock unit which represents a deferred stock unit is the economic equivalent of one share of Community Financial System, Inc. common stock and will be settled in common stock at a predetermined date."},{"field":"derivative.expiration_date","element":"expirationDate","label":"F3","text":"The reporting person has received deferred stock units under the Community Financial System, Inc. 2022 Long-Term Incentive Plan, as amended (the \"LTIP\"). Each phantom stock unit which represents a deferred stock unit is the economic equivalent of one share of Community Financial System, Inc. common stock and will be settled in common stock at a predetermined date."}],"balance_after":7136.111,"derivative":{"underlying":"Common Stock","underlying_shares":1254},"source":{"system":"sec-edgar","filing":"0000723188-26-000082","document":"form4.xml","document_sequence":1,"table":"derivative","row_type":"transaction","position":3,"url":"https://www.sec.gov/Archives/edgar/data/723188/000072318826000082/form4.xml","form_type":"4"}},{"id":831625,"issuer":{"id":4178,"kind":"organization","name":"COMMUNITY FINANCIAL SYSTEM, INC.","symbol":"CBU"},"owners":[{"id":50447,"kind":"person","name":"Pecor Raymond C III","position":1,"cik":"0001475265","reported_name":"Pecor Raymond C III","relationship":{"director":true}}],"security":"Common Stock","published_at":"2026-03-23T15:09:40.000Z","date":"2026-03-19","kind":"exercise","planned":false,"acquired":true,"shares":1254,"ownership":{"direct":true},"footnotes":[{"field":"price","element":"transactionPricePerShare","label":"F1","text":"On March 19, 2026, the reporting person's phantom stock units were settled for 1,254 shares of Community Financial System, Inc. common stock, and .5514 shares were settled in cash at the price of $55.61 per share."}],"balance_after":11439.221,"source":{"system":"sec-edgar","filing":"0000723188-26-000082","document":"form4.xml","document_sequence":1,"table":"nonDerivative","row_type":"transaction","position":1,"url":"https://www.sec.gov/Archives/edgar/data/723188/000072318826000082/form4.xml","form_type":"4"}},{"id":831624,"issuer":{"id":4178,"kind":"organization","name":"COMMUNITY FINANCIAL SYSTEM, INC.","symbol":"CBU"},"owners":[{"id":50448,"kind":"person","name":"STEELE SALLY A","position":1,"cik":"0001264816","reported_name":"STEELE SALLY A","relationship":{"director":true}}],"security":"Phantom Stock (Deferred Stock Units)","published_at":"2026-03-23T15:06:54.000Z","date":"2026-03-19","kind":"exercise","planned":false,"acquired":false,"shares":1254,"ownership":{"direct":true},"footnotes":[{"field":"derivative.exercise_price","element":"conversionOrExercisePrice","label":"F2","text":"The reporting person has received deferred stock units under the Community Financial System, Inc. 2022 Long-Term Incentive Plan, as amended (the \"LTIP\"). Each phantom stock unit which represents a deferred stock unit is the economic equivalent of one share of Community Financial System, Inc. common stock and will be settled in common stock at a predetermined date."},{"field":"price","element":"transactionPricePerShare","label":"F1","text":"On March 19, 2026, the reporting person's phantom stock units were settled for 1,254 shares of Community Financial System, Inc. common stock, and .5514 shares were settled in cash at the price of $55.61 per share."},{"field":"derivative.exercise_date","element":"exerciseDate","label":"F2","text":"The reporting person has received deferred stock units under the Community Financial System, Inc. 2022 Long-Term Incentive Plan, as amended (the \"LTIP\"). Each phantom stock unit which represents a deferred stock unit is the economic equivalent of one share of Community Financial System, Inc. common stock and will be settled in common stock at a predetermined date."},{"field":"derivative.expiration_date","element":"expirationDate","label":"F2","text":"The reporting person has received deferred stock units under the Community Financial System, Inc. 2022 Long-Term Incentive Plan, as amended (the \"LTIP\"). Each phantom stock unit which represents a deferred stock unit is the economic equivalent of one share of Community Financial System, Inc. common stock and will be settled in common stock at a predetermined date."}],"balance_after":1230.7635,"derivative":{"underlying":"Common Stock","underlying_shares":1254},"source":{"system":"sec-edgar","filing":"0000723188-26-000080","document":"form4.xml","document_sequence":1,"table":"derivative","row_type":"transaction","position":3,"url":"https://www.sec.gov/Archives/edgar/data/723188/000072318826000080/form4.xml","form_type":"4"}},{"id":831623,"issuer":{"id":4178,"kind":"organization","name":"COMMUNITY FINANCIAL SYSTEM, INC.","symbol":"CBU"},"owners":[{"id":50448,"kind":"person","name":"STEELE SALLY A","position":1,"cik":"0001264816","reported_name":"STEELE SALLY A","relationship":{"director":true}}],"security":"Common Stock","published_at":"2026-03-23T15:06:54.000Z","date":"2026-03-19","kind":"exercise","planned":false,"acquired":true,"shares":1254,"ownership":{"direct":true},"footnotes":[{"field":"price","element":"transactionPricePerShare","label":"F1","text":"On March 19, 2026, the reporting person's phantom stock units were settled for 1,254 shares of Community Financial System, Inc. common stock, and .5514 shares were settled in cash at the price of $55.61 per share."}],"balance_after":41218,"source":{"system":"sec-edgar","filing":"0000723188-26-000080","document":"form4.xml","document_sequence":1,"table":"nonDerivative","row_type":"transaction","position":1,"url":"https://www.sec.gov/Archives/edgar/data/723188/000072318826000080/form4.xml","form_type":"4"}},{"id":831622,"issuer":{"id":4178,"kind":"organization","name":"COMMUNITY FINANCIAL SYSTEM, INC.","symbol":"CBU"},"owners":[{"id":50445,"kind":"person","name":"Knauss Jeffery J","position":1,"cik":"0001900543","reported_name":"Knauss Jeffery J","relationship":{"director":true}}],"security":"Phantom Stock (Deferred Stock Units)","published_at":"2026-03-23T15:05:04.000Z","date":"2026-03-19","kind":"exercise","planned":false,"acquired":false,"shares":1254,"ownership":{"direct":true},"footnotes":[{"field":"derivative.exercise_price","element":"conversionOrExercisePrice","label":"F2","text":"The reporting person has received deferred stock units under the Community Financial System, Inc. 2022 Long-Term Incentive Plan, as amended (the \"LTIP\"). Each phantom stock unit which represents a deferred stock unit is the economic equivalent of one share of Community Financial System, Inc. common stock and will be settled in common stock at a predetermined date."},{"field":"price","element":"transactionPricePerShare","label":"F1","text":"On March 19, 2026, the reporting person's phantom stock units were settled for 1,254 shares of Community Financial System, Inc. common stock, and .5514 shares were settled in cash at the price of $55.61 per share."},{"field":"derivative.exercise_date","element":"exerciseDate","label":"F2","text":"The reporting person has received deferred stock units under the Community Financial System, Inc. 2022 Long-Term Incentive Plan, as amended (the \"LTIP\"). Each phantom stock unit which represents a deferred stock unit is the economic equivalent of one share of Community Financial System, Inc. common stock and will be settled in common stock at a predetermined date."},{"field":"derivative.expiration_date","element":"expirationDate","label":"F2","text":"The reporting person has received deferred stock units under the Community Financial System, Inc. 2022 Long-Term Incentive Plan, as amended (the \"LTIP\"). Each phantom stock unit which represents a deferred stock unit is the economic equivalent of one share of Community Financial System, Inc. common stock and will be settled in common stock at a predetermined date."}],"balance_after":1220,"derivative":{"underlying":"Common Stock","underlying_shares":1254},"source":{"system":"sec-edgar","filing":"0000723188-26-000078","document":"form4.xml","document_sequence":1,"table":"derivative","row_type":"transaction","position":2,"url":"https://www.sec.gov/Archives/edgar/data/723188/000072318826000078/form4.xml","form_type":"4"}},{"id":831621,"issuer":{"id":4178,"kind":"organization","name":"COMMUNITY FINANCIAL SYSTEM, INC.","symbol":"CBU"},"owners":[{"id":50445,"kind":"person","name":"Knauss Jeffery J","position":1,"cik":"0001900543","reported_name":"Knauss Jeffery J","relationship":{"director":true}}],"security":"Common Stock","published_at":"2026-03-23T15:05:04.000Z","date":"2026-03-19","kind":"exercise","planned":false,"acquired":true,"shares":1254,"ownership":{"direct":true},"footnotes":[{"field":"price","element":"transactionPricePerShare","label":"F1","text":"On March 19, 2026, the reporting person's phantom stock units were settled for 1,254 shares of Community Financial System, Inc. common stock, and .5514 shares were settled in cash at the price of $55.61 per share."}],"balance_after":4820.4908,"source":{"system":"sec-edgar","filing":"0000723188-26-000078","document":"form4.xml","document_sequence":1,"table":"nonDerivative","row_type":"transaction","position":1,"url":"https://www.sec.gov/Archives/edgar/data/723188/000072318826000078/form4.xml","form_type":"4"}},{"id":831620,"issuer":{"id":4178,"kind":"organization","name":"COMMUNITY FINANCIAL SYSTEM, INC.","symbol":"CBU"},"owners":[{"id":50446,"kind":"person","name":"Parente John","position":1,"cik":"0001486057","reported_name":"Parente John","relationship":{"director":true}}],"security":"Phantom Stock (Deferred Stock Units)","published_at":"2026-03-23T14:49:05.000Z","date":"2026-03-19","kind":"exercise","planned":false,"acquired":false,"shares":1254,"ownership":{"direct":true},"footnotes":[{"field":"derivative.exercise_price","element":"conversionOrExercisePrice","label":"F2","text":"The reporting person has received deferred stock units under the Community Financial System, Inc. 2022 Long-Term Incentive Plan, as amended (the \"LTIP\"). Each phantom stock unit which represents a deferred stock unit is the economic equivalent of one share of Community Financial System, Inc. common stock and will be settled in common stock at a predetermined date."},{"field":"price","element":"transactionPricePerShare","label":"F1","text":"On March 19, 2026, the reporting person's phantom stock units were settled for 1,254 shares of Community Financial System, Inc. common stock, and .5514 shares were settled in cash at the price of $55.61 per share."},{"field":"derivative.exercise_date","element":"exerciseDate","label":"F2","text":"The reporting person has received deferred stock units under the Community Financial System, Inc. 2022 Long-Term Incentive Plan, as amended (the \"LTIP\"). Each phantom stock unit which represents a deferred stock unit is the economic equivalent of one share of Community Financial System, Inc. common stock and will be settled in common stock at a predetermined date."},{"field":"derivative.expiration_date","element":"expirationDate","label":"F2","text":"The reporting person has received deferred stock units under the Community Financial System, Inc. 2022 Long-Term Incentive Plan, as amended (the \"LTIP\"). Each phantom stock unit which represents a deferred stock unit is the economic equivalent of one share of Community Financial System, Inc. common stock and will be settled in common stock at a predetermined date."}],"balance_after":1220,"derivative":{"underlying":"Common Stock","underlying_shares":1254},"source":{"system":"sec-edgar","filing":"0000723188-26-000076","document":"form4.xml","document_sequence":1,"table":"derivative","row_type":"transaction","position":2,"url":"https://www.sec.gov/Archives/edgar/data/723188/000072318826000076/form4.xml","form_type":"4"}},{"id":831619,"issuer":{"id":4178,"kind":"organization","name":"COMMUNITY FINANCIAL SYSTEM, INC.","symbol":"CBU"},"owners":[{"id":50446,"kind":"person","name":"Parente John","position":1,"cik":"0001486057","reported_name":"Parente John","relationship":{"director":true}}],"security":"Common Stock","published_at":"2026-03-23T14:49:05.000Z","date":"2026-03-19","kind":"exercise","planned":false,"acquired":true,"shares":1254,"ownership":{"direct":true},"footnotes":[{"field":"price","element":"transactionPricePerShare","label":"F1","text":"On March 19, 2026, the reporting person's phantom stock units were settled for 1,254 shares of Community Financial System, Inc. common stock, and .5514 shares were settled in cash at the price of $55.61 per share."}],"balance_after":72645.3212,"source":{"system":"sec-edgar","filing":"0000723188-26-000076","document":"form4.xml","document_sequence":1,"table":"nonDerivative","row_type":"transaction","position":1,"url":"https://www.sec.gov/Archives/edgar/data/723188/000072318826000076/form4.xml","form_type":"4"}},{"id":834191,"issuer":{"id":4178,"kind":"organization","name":"COMMUNITY FINANCIAL SYSTEM, INC.","symbol":"CBU"},"owners":[{"id":50447,"kind":"person","name":"Pecor Raymond C III","position":1,"cik":"0001475265","reported_name":"Pecor Raymond C III","relationship":{"director":true}}],"security":"Phantom Stock (Deferred Stock Units)","published_at":"2026-03-19T22:04:36.000Z","date":"2026-03-17","kind":"grant","planned":false,"acquired":true,"shares":1220,"price":0,"value":0.0,"ownership":{"direct":true},"footnotes":[{"field":"derivative.exercise_price","element":"conversionOrExercisePrice","label":"F8","text":"The reporting person has received deferred stock units under the Community Financial System, Inc. 2022 Long-Term Incentive Plan, as amended (the \"LTIP\"). Each phantom stock unit which represents a deferred stock unit is the economic equivalent of one share of Community Financial System, Inc. common stock and will be settled in common stock at a predetermined date."},{"field":"derivative.exercise_date","element":"exerciseDate","label":"F8","text":"The reporting person has received deferred stock units under the Community Financial System, Inc. 2022 Long-Term Incentive Plan, as amended (the \"LTIP\"). Each phantom stock unit which represents a deferred stock unit is the economic equivalent of one share of Community Financial System, Inc. common stock and will be settled in common stock at a predetermined date."},{"field":"derivative.expiration_date","element":"expirationDate","label":"F8","text":"The reporting person has received deferred stock units under the Community Financial System, Inc. 2022 Long-Term Incentive Plan, as amended (the \"LTIP\"). Each phantom stock unit which represents a deferred stock unit is the economic equivalent of one share of Community Financial System, Inc. common stock and will be settled in common stock at a predetermined date."},{"field":"balance_after","element":"sharesOwnedFollowingTransaction","label":"F9","text":"Includes 55.1073 units of phantom stock acquired on January 12, 2026 under the LTIP's dividend reinvestment feature."}],"balance_after":8390.6624,"derivative":{"underlying":"Common Stock","underlying_shares":1220},"source":{"system":"sec-edgar","filing":"0000723188-26-000074","document":"form4.xml","document_sequence":1,"table":"derivative","row_type":"transaction","position":5,"url":"https://www.sec.gov/Archives/edgar/data/723188/000072318826000074/form4.xml","form_type":"4"}},{"id":834190,"issuer":{"id":4178,"kind":"organization","name":"COMMUNITY FINANCIAL SYSTEM, INC.","symbol":"CBU"},"owners":[{"id":49816,"kind":"person","name":"Wlos Marya 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Each phantom stock unit which represents a deferred stock unit is the economic equivalent of one share of Community Bank System, Inc. common stock and will be settled in common stock at a predetermined date."},{"field":"derivative.expiration_date","element":"expirationDate","label":"F1","text":"The reporting person has received deferred stock units under the Community Financial System, Inc. 2022 Long-Term Incentive Plan, as amended (\"LTIP\"). Each phantom stock unit which represents a deferred stock unit is the economic equivalent of one share of Community Bank System, Inc. common stock and will be settled in common stock at a predetermined date."},{"field":"balance_after","element":"sharesOwnedFollowingTransaction","label":"F2","text":"Includes 9.6079 units of phantom stock acquired on January 12, 2026 under the LTIP's dividend reinvestment feature."}],"balance_after":2474.5514,"derivative":{"exercise_price":0,"underlying":"Common Stock","underlying_shares":1220},"source":{"system":"sec-edgar","filing":"0000723188-26-000060","document":"form4.xml","document_sequence":1,"table":"derivative","row_type":"transaction","position":1,"url":"https://www.sec.gov/Archives/edgar/data/723188/000072318826000060/form4.xml","form_type":"4"}},{"id":836182,"issuer":{"id":4178,"kind":"organization","name":"COMMUNITY FINANCIAL SYSTEM, INC.","symbol":"CBU"},"owners":[{"id":47829,"kind":"person","name":"Singh Savneet","position":1,"cik":"0001738659","reported_name":"Singh Savneet","relationship":{"director":true}}],"security":"Phantom Stock (Deferred Stock Units)","published_at":"2026-03-18T18:11:56.000Z","date":"2026-03-17","kind":"grant","planned":false,"acquired":true,"shares":1220,"price":0,"value":0.0,"ownership":{"direct":true},"footnotes":[{"field":"derivative.exercise_price","element":"conversionOrExercisePrice","label":"F3","text":"The reporting person has received deferred stock units under the Community Financial System, Inc. 2022 Long-Term Incentive Plan, as amended (the \"LTIP\"). Each phantom stock unit which represents a deferred stock unit is the economic equivalent of one share of Community Financial System, Inc. common stock and will be settled in common stock at a predetermined date."},{"field":"derivative.exercise_date","element":"exerciseDate","label":"F3","text":"The reporting person has received deferred stock units under the Community Financial System, Inc. 2022 Long-Term Incentive Plan, as amended (the \"LTIP\"). Each phantom stock unit which represents a deferred stock unit is the economic equivalent of one share of Community Financial System, Inc. common stock and will be settled in common stock at a predetermined date."},{"field":"derivative.expiration_date","element":"expirationDate","label":"F3","text":"The reporting person has received deferred stock units under the Community Financial System, Inc. 2022 Long-Term Incentive Plan, as amended (the \"LTIP\"). Each phantom stock unit which represents a deferred stock unit is the economic equivalent of one share of Community Financial System, Inc. common stock and will be settled in common stock at a predetermined date."},{"field":"balance_after","element":"sharesOwnedFollowingTransaction","label":"F4","text":"Includes 9.6079 units of phantom stock acquired on January 12, 2026 under the LTIP's dividend reinvestment feature."}],"balance_after":2474.5514,"derivative":{"underlying":"Common Stock","underlying_shares":1220},"source":{"system":"sec-edgar","filing":"0000723188-26-000059","document":"form4.xml","document_sequence":1,"table":"derivative","row_type":"transaction","position":2,"url":"https://www.sec.gov/Archives/edgar/data/723188/000072318826000059/form4.xml","form_type":"4"}},{"id":836183,"issuer":{"id":4178,"kind":"organization","name":"COMMUNITY FINANCIAL SYSTEM, INC.","symbol":"CBU"},"owners":[{"id":50448,"kind":"person","name":"STEELE SALLY A","position":1,"cik":"0001264816","reported_name":"STEELE SALLY A","relationship":{"director":true}}],"security":"Phantom Stock (Deferred Stock Units)","published_at":"2026-03-18T17:31:49.000Z","date":"2026-03-17","kind":"grant","planned":false,"acquired":true,"shares":1220,"price":0,"value":0.0,"ownership":{"direct":true},"footnotes":[{"field":"derivative.exercise_price","element":"conversionOrExercisePrice","label":"F1","text":"The reporting person has received deferred stock units under the Community Financial System, Inc. 2022 Long-Term Incentive Plan, as amended (the \"LTIP\"). Each phantom stock unit which represents a deferred stock unit is the economic equivalent of one share of Community Financial System, Inc. common stock and will be settled in common stock at a predetermined date."},{"field":"derivative.exercise_date","element":"exerciseDate","label":"F1","text":"The reporting person has received deferred stock units under the Community Financial System, Inc. 2022 Long-Term Incentive Plan, as amended (the \"LTIP\"). Each phantom stock unit which represents a deferred stock unit is the economic equivalent of one share of Community Financial System, Inc. common stock and will be settled in common stock at a predetermined date."},{"field":"derivative.expiration_date","element":"expirationDate","label":"F1","text":"The reporting person has received deferred stock units under the Community Financial System, Inc. 2022 Long-Term Incentive Plan, as amended (the \"LTIP\"). Each phantom stock unit which represents a deferred stock unit is the economic equivalent of one share of Community Financial System, Inc. common stock and will be settled in common stock at a predetermined date."}],"balance_after":2485.3149,"derivative":{"underlying":"Common Stock","underlying_shares":1220},"source":{"system":"sec-edgar","filing":"0000723188-26-000057","document":"form4.xml","document_sequence":1,"table":"derivative","row_type":"transaction","position":1,"url":"https://www.sec.gov/Archives/edgar/data/723188/000072318826000057/form4.xml","form_type":"4"}},{"id":836181,"issuer":{"id":4178,"kind":"organization","name":"COMMUNITY FINANCIAL SYSTEM, INC.","symbol":"CBU"},"owners":[{"id":59660,"kind":"person","name":"Whipple John F.","position":1,"cik":"0001485739","reported_name":"Whipple John F.","relationship":{"director":true}}],"security":"Phantom Stock (Deferred Stock Units)","published_at":"2026-03-18T17:23:36.000Z","date":"2026-03-17","kind":"grant","planned":false,"acquired":true,"shares":1220,"price":0,"value":0.0,"ownership":{"direct":true},"footnotes":[{"field":"derivative.exercise_date","element":"exerciseDate","label":"F3","text":"The reporting person has received deferred stock units under the Community Financial System, Inc. 2022 Long-Term Incentive Plan, as amended (the \"Plan\"). Each phantom stock unit which represents a deferred stock unit is the economic equivalent of one share of Community Financial System, Inc. common stock and will be settled in common stock at a predetermined date."},{"field":"derivative.expiration_date","element":"expirationDate","label":"F3","text":"The reporting person has received deferred stock units under the Community Financial System, Inc. 2022 Long-Term Incentive Plan, as amended (the \"Plan\"). Each phantom stock unit which represents a deferred stock unit is the economic equivalent of one share of Community Financial System, Inc. common stock and will be settled in common stock at a predetermined date."},{"field":"balance_after","element":"sharesOwnedFollowingTransaction","label":"F4","text":"Includes 35.9672, 40.8617, 45.1866, and 41.4544 units of phantom stock acquired on April 10, 2025, July 10, 2025, October 10, 2025, and January 12, 2026, respectively, as dividend equivalents under the Plan."}],"balance_after":6632.8816,"derivative":{"exercise_price":0,"underlying":"Common Stock","underlying_shares":1220},"source":{"system":"sec-edgar","filing":"0000723188-26-000056","document":"form4.xml","document_sequence":1,"table":"derivative","row_type":"transaction","position":2,"url":"https://www.sec.gov/Archives/edgar/data/723188/000072318826000056/form4.xml","form_type":"4"}},{"id":836179,"issuer":{"id":4178,"kind":"organization","name":"COMMUNITY FINANCIAL SYSTEM, INC.","symbol":"CBU"},"owners":[{"id":18897,"kind":"person","name":"Vaccaro John A","position":1,"cik":"0002090100","reported_name":"Vaccaro John A","relationship":{"director":true}}],"security":"Phantom Stock (Deferred Stock Units)","published_at":"2026-03-18T16:54:25.000Z","date":"2026-03-17","kind":"grant","planned":false,"acquired":true,"shares":1220,"price":0,"value":0.0,"ownership":{"direct":true},"footnotes":[{"field":"derivative.exercise_price","element":"conversionOrExercisePrice","label":"F1","text":"The reporting person has received deferred stock units under the Community Financial System, Inc. 2022 Long-Term Incentive Plan, as amended (the \"LTIP\"). Each phantom stock unit which represents a deferred stock unit is the economic equivalent of one share of Community Financial System, Inc. common stock and will be settled in common stock at a predetermined date."},{"field":"derivative.exercise_date","element":"exerciseDate","label":"F1","text":"The reporting person has received deferred stock units under the Community Financial System, Inc. 2022 Long-Term Incentive Plan, as amended (the \"LTIP\"). Each phantom stock unit which represents a deferred stock unit is the economic equivalent of one share of Community Financial System, Inc. common stock and will be settled in common stock at a predetermined date."},{"field":"derivative.expiration_date","element":"expirationDate","label":"F1","text":"The reporting person has received deferred stock units under the Community Financial System, Inc. 2022 Long-Term Incentive Plan, as amended (the \"LTIP\"). Each phantom stock unit which represents a deferred stock unit is the economic equivalent of one share of Community Financial System, Inc. common stock and will be settled in common stock at a predetermined date."}],"balance_after":1220,"derivative":{"underlying":"Common Stock","underlying_shares":1220},"source":{"system":"sec-edgar","filing":"0000723188-26-000055","document":"form4.xml","document_sequence":1,"table":"derivative","row_type":"transaction","position":1,"url":"https://www.sec.gov/Archives/edgar/data/723188/000072318826000055/form4.xml","form_type":"4"}},{"id":836180,"issuer":{"id":4178,"kind":"organization","name":"COMMUNITY FINANCIAL SYSTEM, INC.","symbol":"CBU"},"owners":[{"id":37049,"kind":"person","name":"Sullivan Michele","position":1,"cik":"0002009605","reported_name":"Sullivan Michele","relationship":{"director":true}}],"security":"Phantom Stock (Deferred Stock Units)","published_at":"2026-03-18T16:48:50.000Z","date":"2026-03-17","kind":"grant","planned":false,"acquired":true,"shares":1220,"price":0,"value":0.0,"ownership":{"direct":true},"footnotes":[{"field":"derivative.exercise_price","element":"conversionOrExercisePrice","label":"F3","text":"The reporting person has received deferred stock units under the Community Financial System, Inc. 2022 Long-Term Incentive Plan, as amended (the \"LTIP\"). Each phantom stock unit which represents a deferred stock unit is the economic equivalent of one share of Community Financial System, Inc. common stock and will be settled in common stock at a predetermined date."},{"field":"derivative.exercise_date","element":"exerciseDate","label":"F4","text":"The reporting person has received deferred stock units under the Community Financial System, Inc. 2022 Long-Term Incentive Plan, as amended (the \"Plan\"). Each phantom stock unit which represents a deferred stock unit is the economic equivalent of one share of Community Financial System, Inc. common stock and will be settled in common stock at a predetermined date."},{"field":"derivative.expiration_date","element":"expirationDate","label":"F4","text":"The reporting person has received deferred stock units under the Community Financial System, Inc. 2022 Long-Term Incentive Plan, as amended (the \"Plan\"). Each phantom stock unit which represents a deferred stock unit is the economic equivalent of one share of Community Financial System, Inc. common stock and will be settled in common stock at a predetermined date."},{"field":"balance_after","element":"sharesOwnedFollowingTransaction","label":"F5","text":"Includes 20.9266 units of phantom stock acquired on January 12, 2026 under the Plan's dividend reinvestment feature."}],"balance_after":3952.5219,"derivative":{"underlying":"Common Stock","underlying_shares":1220},"source":{"system":"sec-edgar","filing":"0000723188-26-000053","document":"form4.xml","document_sequence":1,"table":"derivative","row_type":"transaction","position":2,"url":"https://www.sec.gov/Archives/edgar/data/723188/000072318826000053/form4.xml","form_type":"4"}},{"id":836178,"issuer":{"id":4178,"kind":"organization","name":"COMMUNITY FINANCIAL SYSTEM, INC.","symbol":"CBU"},"owners":[{"id":39871,"kind":"person","name":"STICKELS ERIC","position":1,"cik":"0001201821","reported_name":"STICKELS ERIC","relationship":{"director":true}}],"security":"Phantom Stock (Deferred Stock Units)","published_at":"2026-03-18T16:25:53.000Z","date":"2026-03-17","kind":"grant","planned":false,"acquired":true,"shares":1220,"price":0,"value":0.0,"ownership":{"direct":true},"footnotes":[{"field":"derivative.exercise_price","element":"conversionOrExercisePrice","label":"F1","text":"The reporting person has received deferred stock units under the Community Financial System, Inc. 2022 Long-Term Incentive Plan, as amended (the \"LTIP\"). Each phantom stock unit which represents a deferred stock unit is the economic equivalent of one share of Community Financial System, Inc. common stock and will be settled in common stock at a predetermined date."},{"field":"derivative.exercise_date","element":"exerciseDate","label":"F1","text":"The reporting person has received deferred stock units under the Community Financial System, Inc. 2022 Long-Term Incentive Plan, as amended (the \"LTIP\"). Each phantom stock unit which represents a deferred stock unit is the economic equivalent of one share of Community Financial System, Inc. common stock and will be settled in common stock at a predetermined date."},{"field":"derivative.expiration_date","element":"expirationDate","label":"F1","text":"The reporting person has received deferred stock units under the Community Financial System, Inc. 2022 Long-Term Incentive Plan, as amended (the \"LTIP\"). Each phantom stock unit which represents a deferred stock unit is the economic equivalent of one share of Community Financial System, Inc. common stock and will be settled in common stock at a predetermined date."}],"balance_after":5234.5421,"derivative":{"underlying":"Common Stock","underlying_shares":1220},"source":{"system":"sec-edgar","filing":"0000723188-26-000052","document":"form4.xml","document_sequence":1,"table":"derivative","row_type":"transaction","position":1,"url":"https://www.sec.gov/Archives/edgar/data/723188/000072318826000052/form4.xml","form_type":"4"}},{"id":836177,"issuer":{"id":4178,"kind":"organization","name":"COMMUNITY FINANCIAL SYSTEM, INC.","symbol":"CBU"},"owners":[{"id":19693,"kind":"person","name":"Hall Brenda M","position":1,"cik":"0001891706","reported_name":"Hall Brenda M","relationship":{"director":true}}],"security":"Phantom Stock (Deferred Stock Units)","published_at":"2026-03-18T15:54:09.000Z","date":"2026-03-17","kind":"grant","planned":false,"acquired":true,"shares":1220,"price":0,"value":0.0,"ownership":{"direct":true},"footnotes":[{"field":"derivative.exercise_price","element":"conversionOrExercisePrice","label":"F1","text":"The reporting person has received deferred stock units under the Community Financial System, Inc. 2022 Long-Term Incentive Plan, as amended (the \"LTIP\"). Each phantom stock unit which represents a deferred stock unit is the economic equivalent of one share of Community Financial System, Inc. common stock and will be settled in common stock at a predetermined date."},{"field":"derivative.exercise_date","element":"exerciseDate","label":"F1","text":"The reporting person has received deferred stock units under the Community Financial System, Inc. 2022 Long-Term Incentive Plan, as amended (the \"LTIP\"). Each phantom stock unit which represents a deferred stock unit is the economic equivalent of one share of Community Financial System, Inc. common stock and will be settled in common stock at a predetermined date."},{"field":"derivative.expiration_date","element":"expirationDate","label":"F1","text":"The reporting person has received deferred stock units under the Community Financial System, Inc. 2022 Long-Term Incentive Plan, as amended (the \"LTIP\"). Each phantom stock unit which represents a deferred stock unit is the economic equivalent of one share of Community Financial System, Inc. common stock and will be settled in common stock at a predetermined date."}],"balance_after":1220,"derivative":{"underlying":"Common Stock","underlying_shares":1220},"source":{"system":"sec-edgar","filing":"0000723188-26-000051","document":"form4.xml","document_sequence":1,"table":"derivative","row_type":"transaction","position":1,"url":"https://www.sec.gov/Archives/edgar/data/723188/000072318826000051/form4.xml","form_type":"4"}},{"id":840323,"issuer":{"id":4178,"kind":"organization","name":"COMMUNITY FINANCIAL SYSTEM, INC.","symbol":"CBU"},"owners":[{"id":39871,"kind":"person","name":"STICKELS ERIC","position":1,"cik":"0001201821","reported_name":"STICKELS ERIC","relationship":{"director":true}}],"security":"Phantom Stock (Deferred Stock Units)","published_at":"2026-03-17T19:33:43.000Z","date":"2026-03-16","kind":"exercise","planned":false,"acquired":false,"shares":250,"ownership":{"direct":true},"footnotes":[{"field":"derivative.exercise_price","element":"conversionOrExercisePrice","label":"F2","text":"The reporting person has received deferred stock units under the Community Financial System, Inc. 2022 Long-Term Incentive Plan, as amended (the \"LTIP\"). Each phantom stock unit which represents a deferred stock unit is the economic equivalent of one share of Community Financial System, Inc. common stock and will be settled in common stock at a predetermined date."},{"field":"price","element":"transactionPricePerShare","label":"F1","text":"On March 16, 2026, the reporting person's phantom stock units were settled for 250 shares of Community Financial System, Inc. common stock, and .9119 shares were settled in cash at the price of $57.42 per share.\""},{"field":"derivative.exercise_date","element":"exerciseDate","label":"F2","text":"The reporting person has received deferred stock units under the Community Financial System, Inc. 2022 Long-Term Incentive Plan, as amended (the \"LTIP\"). Each phantom stock unit which represents a deferred stock unit is the economic equivalent of one share of Community Financial System, Inc. common stock and will be settled in common stock at a predetermined date."},{"field":"derivative.expiration_date","element":"expirationDate","label":"F2","text":"The reporting person has received deferred stock units under the Community Financial System, Inc. 2022 Long-Term Incentive Plan, as amended (the \"LTIP\"). 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