{"abstract":"The exemption is a dollar lower than stipulated for some excess amounts.","category":"Tax bracket computation","checks":7,"contract":"solve(amti, regular_cents, status): stipulated AMT, whole dollars. Exemption: single 85700 (phase-out threshold 609350), mfj 133300 (threshold 1218700). The exemption is reduced by 25% of AMTI above the threshold, with the reduction rounded down to whole dollars, never below 0. Base = max(0, amti - exemption). Tentative minimum tax = 26% of base up to 232600 plus 28% of base above 232600 (in cents: dollars times percent). AMT = max(0, TMT - regular tax). Return [exemption, tmt_cents, amt_cents].","contract_signature":"amti, regular_cents, status","evaluation_group":"w2-tax_bracket_computation-alternative-minimum-tax","failed_approach":"Rounding the reduction up removes up to a dollar too much.","family":"w2-tax_bracket_computation-alternative-minimum-tax-reduction-rounding","id":"FA-62551","implementations":{"attempt":{"sha256":"a79591596c6da12b5546818c2de7a1ca8e4ac6e19baa319611dd834822ffc16c","source":"\"\"\"Failure Map reference implementation. Python standard library only.\"\"\"\nimport json\n\nN = 1\nobservations = []\ndef solve(amti, regular_cents, status):\n    ex, thr = {'single': (85700, 609350), 'mfj': (133300, 1218700)}[status]\n    if amti > thr: ex = max(0, ex - -(-(amti - thr) // 4))\n    base = max(0, amti - ex)\n    tmt = min(base, 232600) * 26 + max(0, base - 232600) * 28\n    return [ex, tmt, max(0, tmt - regular_cents)]\ndef check(label, actual, expected):\n    observations.append({\"check\": label, \"actual\": actual, \"expected\": expected, \"passed\": actual == expected})\ncases = [[('regression reduction-rounding 1', (609353, 5000000, 'single'), [85700, 14197084, 9197084]),\n  ('regression reduction-rounding 2', (700000, 0, 'single'), [63038, 17369736, 17369736]),\n  ('partial repair guard 2', (609351, 0, 'single'), [85700, 14197028, 14197028]),\n  ('control: moderate single', (200000, 2500000, 'single'), [85700, 2971800, 471800]),\n  ('control: no exemption left', (1000000, 99999999, 'single'), [0, 27534800, 0]),\n  ('control: below exemption', (100000, 0, 'mfj'), [133300, 0, 0]),\n  ('control: joint high', (1300000, 30000000, 'mfj'), [112975, 32771500, 2771500])],\n [('regression reduction-rounding 1', (832985, 0, 'single'), [29792, 22024204, 22024204]),\n  ('regression reduction-rounding 2', (932132, 2500000, 'single'), [5005, 25494356, 22994356]),\n  ('partial repair guard 1', (700000, 0, 'single'), [63038, 17369736, 17369736]),\n  ('control: below exemption', (100000, 0, 'mfj'), [133300, 0, 0]),\n  ('control: odd excess', (609353, 5000000, 'single'), [85700, 14197084, 9197084]),\n  ('control: joint high', (1300000, 30000000, 'mfj'), [112975, 32771500, 2771500]),\n  ('control: rate break', (400000, 0, 'mfj'), [133300, 7002400, 7002400])],\n [('regression reduction-rounding 1', (625793, 19280708, 'single'), [81590, 14772484, 0]),\n  ('regression reduction-rounding 2', (1622278, 2500000, 'mfj'), [32406, 44051216, 41551216]),\n  ('partial repair guard 1', (633603, 10000000, 'single'), [79637, 15045848, 5045848]),\n  ('partial repair guard 2', (853491, 0, 'single'), [24665, 22741928, 22741928]),\n  ('control: rate break', (400000, 0, 'mfj'), [133300, 7002400, 7002400]),\n  ('control: moderate single', (200000, 2500000, 'single'), [85700, 2971800, 471800]),\n  ('control: partial phase-out', (700000, 0, 'single'), [63038, 17369736, 17369736]),\n  ('control: no exemption left', (1000000, 99999999, 'single'), [0, 27534800, 0])],\n [('regression reduction-rounding 1', (1346318, 26048839, 'mfj'), [101396, 34392616, 8343777]),\n  ('regression reduction-rounding 2', (1429526, 0, 'mfj'), [80594, 37304896, 37304896]),\n  ('partial repair guard 1', (730275, 2500000, 'single'), [55469, 18429368, 15929368]),\n  ('partial repair guard 2', (932132, 2500000, 'single'), [5005, 25494356, 22994356]),\n  ('control: no exemption left', (1000000, 99999999, 'single'), [0, 27534800, 0]),\n  ('control: below exemption', (100000, 0, 'mfj'), [133300, 0, 0]),\n  ('control: odd excess', (609353, 5000000, 'single'), [85700, 14197084, 9197084]),\n  ('control: joint high', (1300000, 30000000, 'mfj'), [112975, 32771500, 2771500])],\n [('regression reduction-rounding 1', (1242587, 0, 'mfj'), [127329, 30762024, 30762024]),\n  ('regression reduction-rounding 2', (1233419, 2500000, 'mfj'), [129621, 30441144, 27941144]),\n  ('partial repair guard 1', (867815, 3084875, 'single'), [21084, 23243268, 20158393]),\n  ('partial repair guard 2', (1605745, 31630075, 'mfj'), [36539, 43472568, 11842493]),\n  ('control: joint high', (1300000, 30000000, 'mfj'), [112975, 32771500, 2771500]),\n  ('control: rate break', (400000, 0, 'mfj'), [133300, 7002400, 7002400]),\n  ('control: moderate single', (200000, 2500000, 'single'), [85700, 2971800, 471800]),\n  ('control: partial phase-out', (700000, 0, 'single'), [63038, 17369736, 17369736])]]\nfor label, args, expected in cases[N - 1]:\n    check(label, 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":"883b11b852f71206d90867d6d4cb444da320797fffeb84ffb5e52a7eaccec01a","source":"\"\"\"Failure Map reference implementation. Python standard library only.\"\"\"\nimport json\n\nN = 1\nobservations = []\ndef solve(amti, regular_cents, status):\n    ex, thr = {'single': (85700, 609350), 'mfj': (133300, 1218700)}[status]\n    if amti > thr: ex = max(0, ex - (amti - thr + 2) // 4)\n    base = max(0, amti - ex)\n    tmt = min(base, 232600) * 26 + max(0, base - 232600) * 28\n    return [ex, tmt, max(0, tmt - regular_cents)]\ndef check(label, actual, expected):\n    observations.append({\"check\": label, \"actual\": actual, \"expected\": expected, \"passed\": actual == expected})\ncases = [[('regression reduction-rounding 1', (609353, 5000000, 'single'), [85700, 14197084, 9197084]),\n  ('regression reduction-rounding 2', (700000, 0, 'single'), [63038, 17369736, 17369736]),\n  ('partial repair guard 2', (609351, 0, 'single'), [85700, 14197028, 14197028]),\n  ('control: moderate single', (200000, 2500000, 'single'), [85700, 2971800, 471800]),\n  ('control: no exemption left', (1000000, 99999999, 'single'), [0, 27534800, 0]),\n  ('control: below exemption', (100000, 0, 'mfj'), [133300, 0, 0]),\n  ('control: joint high', (1300000, 30000000, 'mfj'), [112975, 32771500, 2771500])],\n [('regression reduction-rounding 1', (832985, 0, 'single'), [29792, 22024204, 22024204]),\n  ('regression reduction-rounding 2', (932132, 2500000, 'single'), [5005, 25494356, 22994356]),\n  ('partial repair guard 1', (700000, 0, 'single'), [63038, 17369736, 17369736]),\n  ('control: below exemption', (100000, 0, 'mfj'), [133300, 0, 0]),\n  ('control: odd excess', (609353, 5000000, 'single'), [85700, 14197084, 9197084]),\n  ('control: joint high', (1300000, 30000000, 'mfj'), [112975, 32771500, 2771500]),\n  ('control: rate break', (400000, 0, 'mfj'), [133300, 7002400, 7002400])],\n [('regression reduction-rounding 1', (625793, 19280708, 'single'), [81590, 14772484, 0]),\n  ('regression reduction-rounding 2', (1622278, 2500000, 'mfj'), [32406, 44051216, 41551216]),\n  ('partial repair guard 1', (633603, 10000000, 'single'), [79637, 15045848, 5045848]),\n  ('partial repair guard 2', (853491, 0, 'single'), [24665, 22741928, 22741928]),\n  ('control: rate break', (400000, 0, 'mfj'), [133300, 7002400, 7002400]),\n  ('control: moderate single', (200000, 2500000, 'single'), [85700, 2971800, 471800]),\n  ('control: partial phase-out', (700000, 0, 'single'), [63038, 17369736, 17369736]),\n  ('control: no exemption left', (1000000, 99999999, 'single'), [0, 27534800, 0])],\n [('regression reduction-rounding 1', (1346318, 26048839, 'mfj'), [101396, 34392616, 8343777]),\n  ('regression reduction-rounding 2', (1429526, 0, 'mfj'), [80594, 37304896, 37304896]),\n  ('partial repair guard 1', (730275, 2500000, 'single'), [55469, 18429368, 15929368]),\n  ('partial repair guard 2', (932132, 2500000, 'single'), [5005, 25494356, 22994356]),\n  ('control: no exemption left', (1000000, 99999999, 'single'), [0, 27534800, 0]),\n  ('control: below exemption', (100000, 0, 'mfj'), [133300, 0, 0]),\n  ('control: odd excess', (609353, 5000000, 'single'), [85700, 14197084, 9197084]),\n  ('control: joint high', (1300000, 30000000, 'mfj'), [112975, 32771500, 2771500])],\n [('regression reduction-rounding 1', (1242587, 0, 'mfj'), [127329, 30762024, 30762024]),\n  ('regression reduction-rounding 2', (1233419, 2500000, 'mfj'), [129621, 30441144, 27941144]),\n  ('partial repair guard 1', (867815, 3084875, 'single'), [21084, 23243268, 20158393]),\n  ('partial repair guard 2', (1605745, 31630075, 'mfj'), [36539, 43472568, 11842493]),\n  ('control: joint high', (1300000, 30000000, 'mfj'), [112975, 32771500, 2771500]),\n  ('control: rate break', (400000, 0, 'mfj'), [133300, 7002400, 7002400]),\n  ('control: moderate single', (200000, 2500000, 'single'), [85700, 2971800, 471800]),\n  ('control: partial phase-out', (700000, 0, 'single'), [63038, 17369736, 17369736])]]\nfor label, args, expected in cases[N - 1]:\n    check(label, 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, bounded teaching model with a stipulated toy contract; it makes no claim of conformance to any real regulation, standard, or institution's rules. 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-tax_bracket_computation-alternative-minimum-tax-reduction-rounding","generated_at":"2026-09-29T14:47:05.691722+00:00","license":"CC0-1.0","python":"3.12.14","seed":1,"split":"open-access"},"relevance":"Tax computations hinge on which slice, threshold, ordering and rounding rule applies at each step; a misplaced boundary silently misstates liabilities.","root_cause":"The quarter reduction is rounded half-up instead of down.","sha256":"2a448fd5fa4df29bb733fe3a9b87c8f174c20b21c51c22ee38ca7c6d544b8986","title":"The exemption reduction is rounded to the nearest dollar · 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":39.118,"exit_code":1,"observations":[{"actual":[85699,14197112,9197112],"check":"regression reduction-rounding 1","expected":[85700,14197084,9197084],"passed":false},{"actual":[63037,17369764,17369764],"check":"regression reduction-rounding 2","expected":[63038,17369736,17369736],"passed":false},{"actual":[85699,14197056,14197056],"check":"partial repair guard 2","expected":[85700,14197028,14197028],"passed":false},{"actual":[85700,2971800,471800],"check":"control: moderate single","expected":[85700,2971800,471800],"passed":true},{"actual":[0,27534800,0],"check":"control: no exemption left","expected":[0,27534800,0],"passed":true},{"actual":[133300,0,0],"check":"control: below exemption","expected":[133300,0,0],"passed":true},{"actual":[112975,32771500,2771500],"check":"control: joint high","expected":[112975,32771500,2771500],"passed":true}],"passed":false,"stderr":"","stdout":"{\"observations\": [{\"check\": \"regression reduction-rounding 1\", \"actual\": [85699, 14197112, 9197112], \"expected\": [85700, 14197084, 9197084], \"passed\": false}, {\"check\": \"regression reduction-rounding 2\", \"actual\": [63037, 17369764, 17369764], \"expected\": [63038, 17369736, 17369736], \"passed\": false}, {\"check\": \"partial repair guard 2\", \"actual\": [85699, 14197056, 14197056], \"expected\": [85700, 14197028, 14197028], \"passed\": false}, {\"check\": \"control: moderate single\", \"actual\": [85700, 2971800, 471800], \"expected\": [85700, 2971800, 471800], \"passed\": true}, {\"check\": \"control: no exemption left\", \"actual\": [0, 27534800, 0], \"expected\": [0, 27534800, 0], \"passed\": true}, {\"check\": \"control: below exemption\", \"actual\": [133300, 0, 0], \"expected\": [133300, 0, 0], \"passed\": true}, {\"check\": \"control: joint high\", \"actual\": [112975, 32771500, 2771500], \"expected\": [112975, 32771500, 2771500], \"passed\": true}], \"passed\": false}\n"},"broken":{"elapsed_ms":38.223,"exit_code":1,"observations":[{"actual":[85699,14197112,9197112],"check":"regression reduction-rounding 1","expected":[85700,14197084,9197084],"passed":false},{"actual":[63037,17369764,17369764],"check":"regression reduction-rounding 2","expected":[63038,17369736,17369736],"passed":false},{"actual":[85700,14197028,14197028],"check":"partial repair guard 2","expected":[85700,14197028,14197028],"passed":true},{"actual":[85700,2971800,471800],"check":"control: moderate single","expected":[85700,2971800,471800],"passed":true},{"actual":[0,27534800,0],"check":"control: no exemption left","expected":[0,27534800,0],"passed":true},{"actual":[133300,0,0],"check":"control: below exemption","expected":[133300,0,0],"passed":true},{"actual":[112975,32771500,2771500],"check":"control: joint high","expected":[112975,32771500,2771500],"passed":true}],"passed":false,"stderr":"","stdout":"{\"observations\": [{\"check\": \"regression reduction-rounding 1\", \"actual\": [85699, 14197112, 9197112], \"expected\": [85700, 14197084, 9197084], \"passed\": false}, {\"check\": \"regression reduction-rounding 2\", \"actual\": [63037, 17369764, 17369764], \"expected\": [63038, 17369736, 17369736], \"passed\": false}, {\"check\": \"partial repair guard 2\", \"actual\": [85700, 14197028, 14197028], \"expected\": [85700, 14197028, 14197028], \"passed\": true}, {\"check\": \"control: moderate single\", \"actual\": [85700, 2971800, 471800], \"expected\": [85700, 2971800, 471800], \"passed\": true}, {\"check\": \"control: no exemption left\", \"actual\": [0, 27534800, 0], \"expected\": [0, 27534800, 0], \"passed\": true}, {\"check\": \"control: below exemption\", \"actual\": [133300, 0, 0], \"expected\": [133300, 0, 0], \"passed\": true}, {\"check\": \"control: joint high\", \"actual\": [112975, 32771500, 2771500], \"expected\": [112975, 32771500, 2771500], \"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."}}