{"abstract":"Paychecks dated exactly February 15 lose exempt status one day early.","category":"Payroll withholding rules","checks":8,"contract":"Input {claims: [[[y,m,d], exempt]], pay_date [y,m,d]}. The active claim is the latest-dated claim on or before the pay date (claims processed by date; equal dates keep input order, last wins). No claim -> 'single-default'. Non-exempt claim -> 'per-form'. Exempt claim is honored through February 15 of the year after it was filed, inclusive; afterwards 'single-default'.","contract_signature":"x","evaluation_group":"w2-payroll-withholding-w4-exempt-expiry","failed_approach":"The attempt compares only year and month, keeping exemption through the end of February.","family":"w2-payroll-withholding-w4-exempt-expiry-expiry-day-inclusion","id":"FA-59131","implementations":{"attempt":{"sha256":"b53c8b76f77dc7496af447a545b4adc90e8afe807ebee26e9d4dfa8e91ab8e40","source":"\"\"\"Failure Map reference implementation. Python standard library only.\"\"\"\nimport json\n\nN = 1\nobservations = []\ndef solve(x):\n    pay = tuple(x['pay_date'])\n    active = None\n    for date, exempt in sorted(x['claims'], key=lambda c: tuple(c[0])):\n        if tuple(date) <= pay:\n            active = (tuple(date), exempt)\n    if active is None:\n        return 'single-default'\n    if not active[1]:\n        return 'per-form'\n    expiry = (active[0][0] + 1, 2, 15)\n    return 'exempt' if pay[:2] <= expiry[:2] else 'single-default'\ndef check(label, actual, expected):\n    observations.append({\"check\": label, \"actual\": actual, \"expected\": expected, \"passed\": actual == expected})\nfixtures = [[('regression', {'claims': [[[2022, 7, 16], True], [[2024, 7, 18], True]], 'pay_date': [2025, 2, 15]}, 'exempt'), ('regression', {'claims': [[[2024, 2, 8], True]], 'pay_date': [2025, 2, 15]}, 'exempt'), ('partial-repair probe', {'claims': [[[2024, 6, 18], True], [[2024, 1, 24], True], [[2024, 8, 3], True]], 'pay_date': [2025, 2, 16]}, 'single-default'), ('partial-repair probe', {'claims': [[[2022, 3, 17], True]], 'pay_date': [2023, 2, 17]}, 'single-default'), ('normal control', {'claims': [[[2022, 2, 13], True], [[2023, 3, 1], False], [[2022, 3, 22], False]], 'pay_date': [2024, 2, 27]}, 'per-form'), ('normal control', {'claims': [[[2023, 2, 25], False]], 'pay_date': [2025, 12, 24]}, 'per-form'), ('normal control', {'claims': [[[2023, 9, 19], True], [[2023, 8, 5], True], [[2022, 3, 16], False]], 'pay_date': [2023, 9, 19]}, 'exempt'), ('normal control', {'claims': [], 'pay_date': [2025, 2, 4]}, 'single-default')], [('regression', {'claims': [[[2024, 2, 8], True]], 'pay_date': [2025, 2, 15]}, 'exempt'), ('regression', {'claims': [[[2023, 9, 9], True], [[2022, 3, 23], True]], 'pay_date': [2024, 2, 15]}, 'exempt'), ('partial-repair probe', {'claims': [[[2022, 7, 11], True], [[2024, 11, 28], True]], 'pay_date': [2023, 2, 25]}, 'single-default'), ('partial-repair probe', {'claims': [[[2023, 5, 16], True], [[2024, 10, 25], True]], 'pay_date': [2025, 2, 16]}, 'single-default'), ('normal control', {'claims': [[[2023, 7, 12], False], [[2023, 2, 5], False], [[2024, 5, 28], False]], 'pay_date': [2024, 2, 16]}, 'per-form'), ('normal control', {'claims': [[[2022, 7, 27], False], [[2022, 1, 5], True], [[2022, 8, 16], True]], 'pay_date': [2024, 5, 27]}, 'single-default'), ('normal control', {'claims': [[[2023, 4, 5], True]], 'pay_date': [2024, 11, 6]}, 'single-default'), ('normal control', {'claims': [[[2023, 10, 8], True], [[2024, 3, 27], True]], 'pay_date': [2023, 10, 8]}, 'exempt')], [('regression', {'claims': [[[2023, 9, 9], True], [[2022, 3, 23], True]], 'pay_date': [2024, 2, 15]}, 'exempt'), ('regression', {'claims': [[[2022, 5, 3], True]], 'pay_date': [2023, 2, 15]}, 'exempt'), ('partial-repair probe', {'claims': [[[2024, 9, 20], True], [[2022, 9, 28], False]], 'pay_date': [2025, 2, 23]}, 'single-default'), ('partial-repair probe', {'claims': [[[2023, 1, 4], True]], 'pay_date': [2024, 2, 16]}, 'single-default'), ('normal control', {'claims': [], 'pay_date': [2023, 2, 16]}, 'single-default'), ('normal control', {'claims': [], 'pay_date': [2023, 2, 15]}, 'single-default'), ('normal control', {'claims': [[[2024, 1, 17], False]], 'pay_date': [2025, 2, 16]}, 'per-form'), ('normal control', {'claims': [[[2022, 1, 6], False], [[2024, 2, 7], False]], 'pay_date': [2024, 2, 12]}, 'per-form')], [('regression', {'claims': [[[2022, 5, 3], True]], 'pay_date': [2023, 2, 15]}, 'exempt'), ('regression', {'claims': [[[2022, 6, 21], True]], 'pay_date': [2023, 2, 15]}, 'exempt'), ('partial-repair probe', {'claims': [[[2022, 9, 2], True], [[2024, 9, 25], False], [[2023, 4, 4], True]], 'pay_date': [2024, 2, 26]}, 'single-default'), ('partial-repair probe', {'claims': [[[2024, 5, 13], True], [[2024, 1, 6], False]], 'pay_date': [2025, 2, 16]}, 'single-default'), ('normal control', {'claims': [[[2023, 2, 6], True]], 'pay_date': [2024, 2, 13]}, 'exempt'), ('normal control', {'claims': [[[2023, 4, 9], False], [[2024, 8, 26], False], [[2022, 5, 3], False]], 'pay_date': [2024, 7, 21]}, 'per-form'), ('normal control', {'claims': [], 'pay_date': [2023, 2, 27]}, 'single-default'), ('normal control', {'claims': [[[2023, 9, 14], False], [[2024, 8, 7], True], [[2024, 1, 1], True]], 'pay_date': [2023, 9, 14]}, 'per-form')], [('regression', {'claims': [[[2022, 6, 21], True]], 'pay_date': [2023, 2, 15]}, 'exempt'), ('regression', {'claims': [[[2023, 10, 18], True], [[2024, 9, 28], True]], 'pay_date': [2024, 2, 15]}, 'exempt'), ('partial-repair probe', {'claims': [[[2022, 3, 7], True], [[2023, 1, 28], True], [[2022, 12, 8], False]], 'pay_date': [2024, 2, 16]}, 'single-default'), ('partial-repair probe', {'claims': [[[2022, 4, 14], True], [[2023, 9, 6], False], [[2023, 3, 2], True]], 'pay_date': [2023, 2, 16]}, 'single-default'), ('normal control', {'claims': [[[2023, 9, 6], True], [[2023, 1, 17], False], [[2022, 11, 5], True]], 'pay_date': [2025, 2, 16]}, 'single-default'), ('normal control', {'claims': [[[2022, 5, 10], True]], 'pay_date': [2022, 5, 10]}, 'exempt'), ('normal control', {'claims': [[[2023, 10, 8], False], [[2024, 8, 1], False]], 'pay_date': [2023, 2, 16]}, 'single-default'), ('normal control', {'claims': [[[2024, 12, 15], False], [[2023, 9, 28], False]], 'pay_date': [2025, 2, 3]}, 'per-form')]]\nfor i, (label, args, expected) in enumerate(fixtures[N-1]):\n    check(\"%s %d\" % (label, i), solve(args), expected)\nprint(json.dumps({\"observations\": observations, \"passed\": all(x[\"passed\"] for x in observations)}, ensure_ascii=False))\nraise SystemExit(0 if all(x[\"passed\"] for x in observations) else 1)\n"},"broken":{"sha256":"a430f8a59d042141ae56e99bc1c52172e70ada937c36e3093d766471bbc3a0f2","source":"\"\"\"Failure Map reference implementation. Python standard library only.\"\"\"\nimport json\n\nN = 1\nobservations = []\ndef solve(x):\n    pay = tuple(x['pay_date'])\n    active = None\n    for date, exempt in sorted(x['claims'], key=lambda c: tuple(c[0])):\n        if tuple(date) <= pay:\n            active = (tuple(date), exempt)\n    if active is None:\n        return 'single-default'\n    if not active[1]:\n        return 'per-form'\n    expiry = (active[0][0] + 1, 2, 15)\n    return 'exempt' if pay < expiry else 'single-default'\ndef check(label, actual, expected):\n    observations.append({\"check\": label, \"actual\": actual, \"expected\": expected, \"passed\": actual == expected})\nfixtures = [[('regression', {'claims': [[[2022, 7, 16], True], [[2024, 7, 18], True]], 'pay_date': [2025, 2, 15]}, 'exempt'), ('regression', {'claims': [[[2024, 2, 8], True]], 'pay_date': [2025, 2, 15]}, 'exempt'), ('partial-repair probe', {'claims': [[[2024, 6, 18], True], [[2024, 1, 24], True], [[2024, 8, 3], True]], 'pay_date': [2025, 2, 16]}, 'single-default'), ('partial-repair probe', {'claims': [[[2022, 3, 17], True]], 'pay_date': [2023, 2, 17]}, 'single-default'), ('normal control', {'claims': [[[2022, 2, 13], True], [[2023, 3, 1], False], [[2022, 3, 22], False]], 'pay_date': [2024, 2, 27]}, 'per-form'), ('normal control', {'claims': [[[2023, 2, 25], False]], 'pay_date': [2025, 12, 24]}, 'per-form'), ('normal control', {'claims': [[[2023, 9, 19], True], [[2023, 8, 5], True], [[2022, 3, 16], False]], 'pay_date': [2023, 9, 19]}, 'exempt'), ('normal control', {'claims': [], 'pay_date': [2025, 2, 4]}, 'single-default')], [('regression', {'claims': [[[2024, 2, 8], True]], 'pay_date': [2025, 2, 15]}, 'exempt'), ('regression', {'claims': [[[2023, 9, 9], True], [[2022, 3, 23], True]], 'pay_date': [2024, 2, 15]}, 'exempt'), ('partial-repair probe', {'claims': [[[2022, 7, 11], True], [[2024, 11, 28], True]], 'pay_date': [2023, 2, 25]}, 'single-default'), ('partial-repair probe', {'claims': [[[2023, 5, 16], True], [[2024, 10, 25], True]], 'pay_date': [2025, 2, 16]}, 'single-default'), ('normal control', {'claims': [[[2023, 7, 12], False], [[2023, 2, 5], False], [[2024, 5, 28], False]], 'pay_date': [2024, 2, 16]}, 'per-form'), ('normal control', {'claims': [[[2022, 7, 27], False], [[2022, 1, 5], True], [[2022, 8, 16], True]], 'pay_date': [2024, 5, 27]}, 'single-default'), ('normal control', {'claims': [[[2023, 4, 5], True]], 'pay_date': [2024, 11, 6]}, 'single-default'), ('normal control', {'claims': [[[2023, 10, 8], True], [[2024, 3, 27], True]], 'pay_date': [2023, 10, 8]}, 'exempt')], [('regression', {'claims': [[[2023, 9, 9], True], [[2022, 3, 23], True]], 'pay_date': [2024, 2, 15]}, 'exempt'), ('regression', {'claims': [[[2022, 5, 3], True]], 'pay_date': [2023, 2, 15]}, 'exempt'), ('partial-repair probe', {'claims': [[[2024, 9, 20], True], [[2022, 9, 28], False]], 'pay_date': [2025, 2, 23]}, 'single-default'), ('partial-repair probe', {'claims': [[[2023, 1, 4], True]], 'pay_date': [2024, 2, 16]}, 'single-default'), ('normal control', {'claims': [], 'pay_date': [2023, 2, 16]}, 'single-default'), ('normal control', {'claims': [], 'pay_date': [2023, 2, 15]}, 'single-default'), ('normal control', {'claims': [[[2024, 1, 17], False]], 'pay_date': [2025, 2, 16]}, 'per-form'), ('normal control', {'claims': [[[2022, 1, 6], False], [[2024, 2, 7], False]], 'pay_date': [2024, 2, 12]}, 'per-form')], [('regression', {'claims': [[[2022, 5, 3], True]], 'pay_date': [2023, 2, 15]}, 'exempt'), ('regression', {'claims': [[[2022, 6, 21], True]], 'pay_date': [2023, 2, 15]}, 'exempt'), ('partial-repair probe', {'claims': [[[2022, 9, 2], True], [[2024, 9, 25], False], [[2023, 4, 4], True]], 'pay_date': [2024, 2, 26]}, 'single-default'), ('partial-repair probe', {'claims': [[[2024, 5, 13], True], [[2024, 1, 6], False]], 'pay_date': [2025, 2, 16]}, 'single-default'), ('normal control', {'claims': [[[2023, 2, 6], True]], 'pay_date': [2024, 2, 13]}, 'exempt'), ('normal control', {'claims': [[[2023, 4, 9], False], [[2024, 8, 26], False], [[2022, 5, 3], False]], 'pay_date': [2024, 7, 21]}, 'per-form'), ('normal control', {'claims': [], 'pay_date': [2023, 2, 27]}, 'single-default'), ('normal control', {'claims': [[[2023, 9, 14], False], [[2024, 8, 7], True], [[2024, 1, 1], True]], 'pay_date': [2023, 9, 14]}, 'per-form')], [('regression', {'claims': [[[2022, 6, 21], True]], 'pay_date': [2023, 2, 15]}, 'exempt'), ('regression', {'claims': [[[2023, 10, 18], True], [[2024, 9, 28], True]], 'pay_date': [2024, 2, 15]}, 'exempt'), ('partial-repair probe', {'claims': [[[2022, 3, 7], True], [[2023, 1, 28], True], [[2022, 12, 8], False]], 'pay_date': [2024, 2, 16]}, 'single-default'), ('partial-repair probe', {'claims': [[[2022, 4, 14], True], [[2023, 9, 6], False], [[2023, 3, 2], True]], 'pay_date': [2023, 2, 16]}, 'single-default'), ('normal control', {'claims': [[[2023, 9, 6], True], [[2023, 1, 17], False], [[2022, 11, 5], True]], 'pay_date': [2025, 2, 16]}, 'single-default'), ('normal control', {'claims': [[[2022, 5, 10], True]], 'pay_date': [2022, 5, 10]}, 'exempt'), ('normal control', {'claims': [[[2023, 10, 8], False], [[2024, 8, 1], False]], 'pay_date': [2023, 2, 16]}, 'single-default'), ('normal control', {'claims': [[[2024, 12, 15], False], [[2023, 9, 28], False]], 'pay_date': [2025, 2, 3]}, 'per-form')]]\nfor i, (label, args, expected) in enumerate(fixtures[N-1]):\n    check(\"%s %d\" % (label, i), solve(args), expected)\nprint(json.dumps({\"observations\": observations, \"passed\": all(x[\"passed\"] for x in observations)}, ensure_ascii=False))\nraise SystemExit(0 if all(x[\"passed\"] for x in observations) else 1)\n"}},"limitations":"A deterministic teaching model of a stipulated payroll rule with toy thresholds and rates. It makes no claim of conformance to any tax authority, statute or jurisdiction and is not payroll software. This reproducer isolates one failure mechanism. Results cover the supplied fixtures. Variants within a family share a test contract and should remain grouped when constructing evaluation splits. Related mechanisms with a shared evaluation_group must also remain together; these controlled models are not independent production incidents.","method":"Deterministic executable model with adversarial boundary fixtures.","provenance":{"created_by":"Failure Map","dependencies":"Python standard library","family":"w2-payroll-withholding-w4-exempt-expiry-expiry-day-inclusion","generated_at":"2026-09-29T14:46:33.409640+00:00","license":"CC0-1.0","python":"3.12.14","seed":1,"split":"open-access"},"relevance":"Exempt status must lapse on a fixed date, reverting to default withholding until a new form arrives.","root_cause":"The expiry comparison is exclusive of February 15.","sha256":"a74de5928a1254897d8f297d29148431e727442f93b414d02bcb4786423a47f2","title":"W-4 exempt claim expiration: expiry day inclusion · case 01","variant":1,"variant_policy":"Five numbered records share a model and may reuse boundary fixtures.","verified":true,"visibility":"public","verification":{"attempt":{"elapsed_ms":39.99,"exit_code":1,"observations":[{"actual":"exempt","check":"regression 0","expected":"exempt","passed":true},{"actual":"exempt","check":"regression 1","expected":"exempt","passed":true},{"actual":"exempt","check":"partial-repair probe 2","expected":"single-default","passed":false},{"actual":"exempt","check":"partial-repair probe 3","expected":"single-default","passed":false},{"actual":"per-form","check":"normal control 4","expected":"per-form","passed":true},{"actual":"per-form","check":"normal control 5","expected":"per-form","passed":true},{"actual":"exempt","check":"normal control 6","expected":"exempt","passed":true},{"actual":"single-default","check":"normal control 7","expected":"single-default","passed":true}],"passed":false,"stderr":"","stdout":"{\"observations\": [{\"check\": \"regression 0\", \"actual\": \"exempt\", \"expected\": \"exempt\", \"passed\": true}, {\"check\": \"regression 1\", \"actual\": \"exempt\", \"expected\": \"exempt\", \"passed\": true}, {\"check\": \"partial-repair probe 2\", \"actual\": \"exempt\", \"expected\": \"single-default\", \"passed\": false}, {\"check\": \"partial-repair probe 3\", \"actual\": \"exempt\", \"expected\": \"single-default\", \"passed\": false}, {\"check\": \"normal control 4\", \"actual\": \"per-form\", \"expected\": \"per-form\", \"passed\": true}, {\"check\": \"normal control 5\", \"actual\": \"per-form\", \"expected\": \"per-form\", \"passed\": true}, {\"check\": \"normal control 6\", \"actual\": \"exempt\", \"expected\": \"exempt\", \"passed\": true}, {\"check\": \"normal control 7\", \"actual\": \"single-default\", \"expected\": \"single-default\", \"passed\": true}], \"passed\": false}\n"},"broken":{"elapsed_ms":40.487,"exit_code":1,"observations":[{"actual":"single-default","check":"regression 0","expected":"exempt","passed":false},{"actual":"single-default","check":"regression 1","expected":"exempt","passed":false},{"actual":"single-default","check":"partial-repair probe 2","expected":"single-default","passed":true},{"actual":"single-default","check":"partial-repair probe 3","expected":"single-default","passed":true},{"actual":"per-form","check":"normal control 4","expected":"per-form","passed":true},{"actual":"per-form","check":"normal control 5","expected":"per-form","passed":true},{"actual":"exempt","check":"normal control 6","expected":"exempt","passed":true},{"actual":"single-default","check":"normal control 7","expected":"single-default","passed":true}],"passed":false,"stderr":"","stdout":"{\"observations\": [{\"check\": \"regression 0\", \"actual\": \"single-default\", \"expected\": \"exempt\", \"passed\": false}, {\"check\": \"regression 1\", \"actual\": \"single-default\", \"expected\": \"exempt\", \"passed\": false}, {\"check\": \"partial-repair probe 2\", \"actual\": \"single-default\", \"expected\": \"single-default\", \"passed\": true}, {\"check\": \"partial-repair probe 3\", \"actual\": \"single-default\", \"expected\": \"single-default\", \"passed\": true}, {\"check\": \"normal control 4\", \"actual\": \"per-form\", \"expected\": \"per-form\", \"passed\": true}, {\"check\": \"normal control 5\", \"actual\": \"per-form\", \"expected\": \"per-form\", \"passed\": true}, {\"check\": \"normal control 6\", \"actual\": \"exempt\", \"expected\": \"exempt\", \"passed\": true}, {\"check\": \"normal control 7\", \"actual\": \"single-default\", \"expected\": \"single-default\", \"passed\": true}], \"passed\": false}\n"}},"member_only":{"stages":["fixed"],"fields":["implementations.fixed","verification.fixed","harness","repair"],"note":"The verified repair, its recorded checks, the repair description, and the scoring harness are available to members."}}