{"abstract":"Couples pay the surcharge from half the stipulated joint limit.","category":"Tax bracket computation","checks":7,"contract":"solve(income_tax, joint): stipulated surcharge on income tax, in integer cents. The exemption limit is 1813000 (doubled for joint assessment). At or below it the surcharge is 0; above it the surcharge is the lesser of 5.5% of the income tax and 11.9% of the excess over the limit (a gliding zone), rounded down to cents.","contract_signature":"income_tax, joint","evaluation_group":"w2-tax_bracket_computation-surcharge-exemption-limit-glide","failed_approach":"Doubling the limit only in the exemption test leaves the glide measured from the single limit.","family":"w2-tax_bracket_computation-surcharge-exemption-limit-glide-joint-limit","id":"FA-62806","implementations":{"attempt":{"sha256":"d2b5c19bc634372aa74a65c39dbb6e0122b6a0ae382c931b2992543332e261c9","source":"\"\"\"Failure Map reference implementation. Python standard library only.\"\"\"\nimport json\nfrom fractions import Fraction\nN = 1\nobservations = []\ndef solve(income_tax, joint):\n    thr = 1813000\n    if income_tax <= thr * (2 if joint else 1): return 0\n    soli = min(income_tax * Fraction(55, 1000), (income_tax - thr) * Fraction(119, 1000))\n    return int(soli)\ndef check(label, actual, expected):\n    observations.append({\"check\": label, \"actual\": actual, \"expected\": expected, \"passed\": actual == expected})\ncases = [[('regression joint-limit 1', (3700000, True), 8806), ('regression joint-limit 2', (3000000, True), 0),\n  ('partial repair guard 2', (3626001, True), 0), ('control: at limit', (1813000, False), 0),\n  ('control: gliding zone', (1900000, False), 10353), ('control: full rate', (5000000, False), 275000),\n  ('control: glide edge', (3300000, False), 176953)],\n [('regression joint-limit 1', (1813009, True), 0), ('regression joint-limit 2', (3626001, True), 0),\n  ('partial repair guard 1', (4499538, True), 103951), ('partial repair guard 2', (4442992, True), 97222),\n  ('control: joint glide', (3700000, True), 8806), ('control: joint below', (3000000, True), 0),\n  ('control: glide edge', (3300000, False), 176953), ('control: at limit', (1813000, False), 0)],\n [('regression joint-limit 1', (4499538, True), 103951), ('regression joint-limit 2', (2007148, True), 0),\n  ('partial repair guard 1', (3675221, True), 5857), ('partial repair guard 2', (5462037, True), 218488),\n  ('control: at limit', (1813000, False), 0), ('control: gliding zone', (1900000, False), 10353),\n  ('control: full rate', (5000000, False), 275000), ('control: joint glide', (3700000, True), 8806)],\n [('regression joint-limit 1', (2212099, True), 0), ('regression joint-limit 2', (3158865, True), 0),\n  ('partial repair guard 1', (5229138, True), 190773), ('partial repair guard 2', (5134546, True), 179516),\n  ('control: joint glide', (3700000, True), 8806), ('control: joint below', (3000000, True), 0),\n  ('control: glide edge', (3300000, False), 176953), ('control: at limit', (1813000, False), 0)],\n [('regression joint-limit 1', (2685272, True), 0), ('regression joint-limit 2', (2964428, True), 0),\n  ('partial repair guard 1', (4465171, True), 99861), ('partial repair guard 2', (3657037, True), 3693),\n  ('control: at limit', (1813000, False), 0), ('control: gliding zone', (1900000, False), 10353),\n  ('control: full rate', (5000000, False), 275000), ('control: joint glide', (3700000, True), 8806)]]\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":"6962f9c673f6fb3bd41348418011e1a76b1299ac5b5b9fb1c60351c0b21e142b","source":"\"\"\"Failure Map reference implementation. Python standard library only.\"\"\"\nimport json\nfrom fractions import Fraction\nN = 1\nobservations = []\ndef solve(income_tax, joint):\n    thr = 1813000\n    if income_tax <= thr: return 0\n    soli = min(income_tax * Fraction(55, 1000), (income_tax - thr) * Fraction(119, 1000))\n    return int(soli)\ndef check(label, actual, expected):\n    observations.append({\"check\": label, \"actual\": actual, \"expected\": expected, \"passed\": actual == expected})\ncases = [[('regression joint-limit 1', (3700000, True), 8806), ('regression joint-limit 2', (3000000, True), 0),\n  ('partial repair guard 2', (3626001, True), 0), ('control: at limit', (1813000, False), 0),\n  ('control: gliding zone', (1900000, False), 10353), ('control: full rate', (5000000, False), 275000),\n  ('control: glide edge', (3300000, False), 176953)],\n [('regression joint-limit 1', (1813009, True), 0), ('regression joint-limit 2', (3626001, True), 0),\n  ('partial repair guard 1', (4499538, True), 103951), ('partial repair guard 2', (4442992, True), 97222),\n  ('control: joint glide', (3700000, True), 8806), ('control: joint below', (3000000, True), 0),\n  ('control: glide edge', (3300000, False), 176953), ('control: at limit', (1813000, False), 0)],\n [('regression joint-limit 1', (4499538, True), 103951), ('regression joint-limit 2', (2007148, True), 0),\n  ('partial repair guard 1', (3675221, True), 5857), ('partial repair guard 2', (5462037, True), 218488),\n  ('control: at limit', (1813000, False), 0), ('control: gliding zone', (1900000, False), 10353),\n  ('control: full rate', (5000000, False), 275000), ('control: joint glide', (3700000, True), 8806)],\n [('regression joint-limit 1', (2212099, True), 0), ('regression joint-limit 2', (3158865, True), 0),\n  ('partial repair guard 1', (5229138, True), 190773), ('partial repair guard 2', (5134546, True), 179516),\n  ('control: joint glide', (3700000, True), 8806), ('control: joint below', (3000000, True), 0),\n  ('control: glide edge', (3300000, False), 176953), ('control: at limit', (1813000, False), 0)],\n [('regression joint-limit 1', (2685272, True), 0), ('regression joint-limit 2', (2964428, True), 0),\n  ('partial repair guard 1', (4465171, True), 99861), ('partial repair guard 2', (3657037, True), 3693),\n  ('control: at limit', (1813000, False), 0), ('control: gliding zone', (1900000, False), 10353),\n  ('control: full rate', (5000000, False), 275000), ('control: joint glide', (3700000, True), 8806)]]\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-surcharge-exemption-limit-glide-joint-limit","generated_at":"2026-09-29T14:47:08.086122+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 exemption limit is not doubled for joint assessment.","sha256":"e7d4227e827c7260d1555e62db870dc01bddc6805e65c1569ce43083781f70e2","title":"Joint assessments use the single exemption limit · 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":50.857,"exit_code":1,"observations":[{"actual":203500,"check":"regression joint-limit 1","expected":8806,"passed":false},{"actual":0,"check":"regression joint-limit 2","expected":0,"passed":true},{"actual":199430,"check":"partial repair guard 2","expected":0,"passed":false},{"actual":0,"check":"control: at limit","expected":0,"passed":true},{"actual":10353,"check":"control: gliding zone","expected":10353,"passed":true},{"actual":275000,"check":"control: full rate","expected":275000,"passed":true},{"actual":176953,"check":"control: glide edge","expected":176953,"passed":true}],"passed":false,"stderr":"","stdout":"{\"observations\": [{\"check\": \"regression joint-limit 1\", \"actual\": 203500, \"expected\": 8806, \"passed\": false}, {\"check\": \"regression joint-limit 2\", \"actual\": 0, \"expected\": 0, \"passed\": true}, {\"check\": \"partial repair guard 2\", \"actual\": 199430, \"expected\": 0, \"passed\": false}, {\"check\": \"control: at limit\", \"actual\": 0, \"expected\": 0, \"passed\": true}, {\"check\": \"control: gliding zone\", \"actual\": 10353, \"expected\": 10353, \"passed\": true}, {\"check\": \"control: full rate\", \"actual\": 275000, \"expected\": 275000, \"passed\": true}, {\"check\": \"control: glide edge\", \"actual\": 176953, \"expected\": 176953, \"passed\": true}], \"passed\": false}\n"},"broken":{"elapsed_ms":49.104,"exit_code":1,"observations":[{"actual":203500,"check":"regression joint-limit 1","expected":8806,"passed":false},{"actual":141253,"check":"regression joint-limit 2","expected":0,"passed":false},{"actual":199430,"check":"partial repair guard 2","expected":0,"passed":false},{"actual":0,"check":"control: at limit","expected":0,"passed":true},{"actual":10353,"check":"control: gliding zone","expected":10353,"passed":true},{"actual":275000,"check":"control: full rate","expected":275000,"passed":true},{"actual":176953,"check":"control: glide edge","expected":176953,"passed":true}],"passed":false,"stderr":"","stdout":"{\"observations\": [{\"check\": \"regression joint-limit 1\", \"actual\": 203500, \"expected\": 8806, \"passed\": false}, {\"check\": \"regression joint-limit 2\", \"actual\": 141253, \"expected\": 0, \"passed\": false}, {\"check\": \"partial repair guard 2\", \"actual\": 199430, \"expected\": 0, \"passed\": false}, {\"check\": \"control: at limit\", \"actual\": 0, \"expected\": 0, \"passed\": true}, {\"check\": \"control: gliding zone\", \"actual\": 10353, \"expected\": 10353, \"passed\": true}, {\"check\": \"control: full rate\", \"actual\": 275000, \"expected\": 275000, \"passed\": true}, {\"check\": \"control: glide edge\", \"actual\": 176953, \"expected\": 176953, \"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."}}