{"abstract":"The exemption disappears for filers barely over the threshold.","category":"Tax bracket computation","checks":6,"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":"Measuring the excess over the exemption amount instead of the threshold still over-reduces.","family":"w2-tax_bracket_computation-alternative-minimum-tax-phaseout-base","id":"FA-62531","implementations":{"attempt":{"sha256":"da463b7f4cbf6b3cfffde5a50ab30b25039d4764d23c69ef4a1600aef01c2f85","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 - ex) // 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 phaseout-base 1', (700000, 0, 'single'), [63038, 17369736, 17369736]),\n  ('regression phaseout-base 2', (609353, 5000000, 'single'), [85700, 14197084, 9197084]),\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 phaseout-base 1', (1300000, 30000000, 'mfj'), [112975, 32771500, 2771500]),\n  ('regression phaseout-base 2', (832985, 0, 'single'), [29792, 22024204, 22024204]),\n  ('control: below exemption', (100000, 0, 'mfj'), [133300, 0, 0]),\n  ('control: odd excess', (609353, 5000000, 'single'), [85700, 14197084, 9197084]),\n  ('control: rate break', (400000, 0, 'mfj'), [133300, 7002400, 7002400]),\n  ('control: moderate single', (200000, 2500000, 'single'), [85700, 2971800, 471800])],\n [('regression phaseout-base 1', (633603, 10000000, 'single'), [79637, 15045848, 5045848]),\n  ('regression phaseout-base 2', (869146, 10000000, 'single'), [20751, 23289860, 13289860]),\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 phaseout-base 1', (853491, 0, 'single'), [24665, 22741928, 22741928]),\n  ('regression phaseout-base 2', (1388032, 0, 'mfj'), [90967, 35852620, 35852620]),\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 phaseout-base 1', (730275, 2500000, 'single'), [55469, 18429368, 15929368]),\n  ('regression phaseout-base 2', (932132, 2500000, 'single'), [5005, 25494356, 22994356]),\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":"7aa8403c400983478899d4d3698d652ee8fced51054e5c8cc375d1e1baeb129f","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 // 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 phaseout-base 1', (700000, 0, 'single'), [63038, 17369736, 17369736]),\n  ('regression phaseout-base 2', (609353, 5000000, 'single'), [85700, 14197084, 9197084]),\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 phaseout-base 1', (1300000, 30000000, 'mfj'), [112975, 32771500, 2771500]),\n  ('regression phaseout-base 2', (832985, 0, 'single'), [29792, 22024204, 22024204]),\n  ('control: below exemption', (100000, 0, 'mfj'), [133300, 0, 0]),\n  ('control: odd excess', (609353, 5000000, 'single'), [85700, 14197084, 9197084]),\n  ('control: rate break', (400000, 0, 'mfj'), [133300, 7002400, 7002400]),\n  ('control: moderate single', (200000, 2500000, 'single'), [85700, 2971800, 471800])],\n [('regression phaseout-base 1', (633603, 10000000, 'single'), [79637, 15045848, 5045848]),\n  ('regression phaseout-base 2', (869146, 10000000, 'single'), [20751, 23289860, 13289860]),\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 phaseout-base 1', (853491, 0, 'single'), [24665, 22741928, 22741928]),\n  ('regression phaseout-base 2', (1388032, 0, 'mfj'), [90967, 35852620, 35852620]),\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 phaseout-base 1', (730275, 2500000, 'single'), [55469, 18429368, 15929368]),\n  ('regression phaseout-base 2', (932132, 2500000, 'single'), [5005, 25494356, 22994356]),\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-phaseout-base","generated_at":"2026-09-29T14:47:05.399404+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 25% reduction is applied to all AMTI rather than AMTI above the threshold.","sha256":"9a112261f14518812d611c46c6971b4dfa9831c820d336de4f178bb1c9fa340c","title":"The exemption phase-out is computed on total AMTI instead of the excess · 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":42.06,"exit_code":1,"observations":[{"actual":[0,19134800,19134800],"check":"regression phaseout-base 1","expected":[63038,17369736,17369736],"passed":false},{"actual":[0,16596684,11596684],"check":"regression phaseout-base 2","expected":[85700,14197084,9197084],"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":[0,35934800,5934800],"check":"control: joint high","expected":[112975,32771500,2771500],"passed":false}],"passed":false,"stderr":"","stdout":"{\"observations\": [{\"check\": \"regression phaseout-base 1\", \"actual\": [0, 19134800, 19134800], \"expected\": [63038, 17369736, 17369736], \"passed\": false}, {\"check\": \"regression phaseout-base 2\", \"actual\": [0, 16596684, 11596684], \"expected\": [85700, 14197084, 9197084], \"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\": [0, 35934800, 5934800], \"expected\": [112975, 32771500, 2771500], \"passed\": false}], \"passed\": false}\n"},"broken":{"elapsed_ms":39.969,"exit_code":1,"observations":[{"actual":[0,19134800,19134800],"check":"regression phaseout-base 1","expected":[63038,17369736,17369736],"passed":false},{"actual":[0,16596684,11596684],"check":"regression phaseout-base 2","expected":[85700,14197084,9197084],"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":[0,35934800,5934800],"check":"control: joint high","expected":[112975,32771500,2771500],"passed":false}],"passed":false,"stderr":"","stdout":"{\"observations\": [{\"check\": \"regression phaseout-base 1\", \"actual\": [0, 19134800, 19134800], \"expected\": [63038, 17369736, 17369736], \"passed\": false}, {\"check\": \"regression phaseout-base 2\", \"actual\": [0, 16596684, 11596684], \"expected\": [85700, 14197084, 9197084], \"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\": [0, 35934800, 5934800], \"expected\": [112975, 32771500, 2771500], \"passed\": false}], \"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."}}