{"abstract":"Filers with large nonrefundable credits pay local surtax on tax they never owed.","category":"Tax bracket computation","checks":6,"contract":"solve(state, nonref, ref, pct): amounts in integer cents; pct a decimal percentage string. State tax after nonrefundable credits is max(0, state - nonref). The local surtax is pct% of that amount, rounded half-up to cents. Refundable credits then apply to the combined total in full (a negative total is a refund). Return [local, total].","evaluation_group":"w2-tax_bracket_computation-local-piggyback-surtax","failed_approach":"Also deducting refundable credits from the base under-charges the surtax.","family":"w2-tax_bracket_computation-local-piggyback-surtax-surtax-base","id":"FA-62686","implementations":{"attempt":{"sha256":"af70bf138f2dfd057500e04caf3bc0ea3635d4dfe9b75174de30f86476b0e19a","source":"\"\"\"Failure Map reference implementation. Python standard library only.\"\"\"\nimport json\nfrom fractions import Fraction\nN = 1\nobservations = []\ndef solve(state, nonref, ref, pct):\n    after = max(0, state - nonref)\n    local = int(max(0, after - ref) * Fraction(pct) / 100 + Fraction(1, 2))\n    return [local, after + local - ref]\ndef check(label, actual, expected):\n    observations.append({\"check\": label, \"actual\": actual, \"expected\": expected, \"passed\": actual == expected})\ncases = [[('regression surtax-base 1', (100000, 20000, 5000, '17.5'), [14000, 89000]),\n  ('regression surtax-base 2', (1000, 3000, 500, '20'), [0, -500]),\n  ('partial repair guard 2', (5000, 1000, 9000, '12.5'), [500, -4500]),\n  ('control: rounding', (333, 0, 0, '1.5'), [5, 338]), ('control: half cent', (1001, 0, 0, '50'), [501, 1502]),\n  ('control: no surtax', (4200, 100, 0, '0'), [0, 4100])],\n [('regression surtax-base 1', (5000, 1000, 9000, '12.5'), [500, -4500]),\n  ('regression surtax-base 2', (143686, 20000, 9000, '17.5'), [21645, 136331]),\n  ('partial repair guard 2', (86323, 79662, 500, '12.5'), [833, 6994]),\n  ('control: half cent', (1001, 0, 0, '50'), [501, 1502]), ('control: no surtax', (4200, 100, 0, '0'), [0, 4100]),\n  ('control: typical', (100000, 20000, 5000, '17.5'), [14000, 89000]),\n  ('control: credits exceed tax', (1000, 3000, 500, '20'), [0, -500])],\n [('regression surtax-base 1', (133783, 45064, 0, '17.5'), [15526, 104245]),\n  ('regression surtax-base 2', (27192, 1000, 0, '12.5'), [3274, 29466]),\n  ('partial repair guard 1', (44678, 28763, 500, '50'), [7958, 23373]),\n  ('partial repair guard 2', (176644, 20000, 500, '8'), [12532, 168676]),\n  ('control: typical', (100000, 20000, 5000, '17.5'), [14000, 89000]),\n  ('control: credits exceed tax', (1000, 3000, 500, '20'), [0, -500]),\n  ('control: rounding', (333, 0, 0, '1.5'), [5, 338]),\n  ('control: large refund', (5000, 1000, 9000, '12.5'), [500, -4500])],\n [('regression surtax-base 1', (86323, 79662, 500, '12.5'), [833, 6994]),\n  ('regression surtax-base 2', (44678, 28763, 500, '50'), [7958, 23373]),\n  ('partial repair guard 1', (107676, 1000, 9000, '8'), [8534, 106210]),\n  ('partial repair guard 2', (96269, 20000, 9000, '8'), [6102, 73371]),\n  ('control: large refund', (5000, 1000, 9000, '12.5'), [500, -4500]),\n  ('control: half cent', (1001, 0, 0, '50'), [501, 1502]), ('control: no surtax', (4200, 100, 0, '0'), [0, 4100]),\n  ('control: typical', (100000, 20000, 5000, '17.5'), [14000, 89000])],\n [('regression surtax-base 1', (176644, 20000, 500, '8'), [12532, 168676]),\n  ('regression surtax-base 2', (107676, 1000, 9000, '8'), [8534, 106210]),\n  ('partial repair guard 1', (171795, 55836, 500, '1.5'), [1739, 117198]),\n  ('partial repair guard 2', (195423, 1000, 9000, '17.5'), [34024, 219447]),\n  ('control: typical', (100000, 20000, 5000, '17.5'), [14000, 89000]),\n  ('control: credits exceed tax', (1000, 3000, 500, '20'), [0, -500]),\n  ('control: rounding', (333, 0, 0, '1.5'), [5, 338]),\n  ('control: large refund', (5000, 1000, 9000, '12.5'), [500, -4500])]]\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":"4423fc47e87040d0f52ce7fc5e587e7ae87f188e7b3c531e362f8ca63e310305","source":"\"\"\"Failure Map reference implementation. Python standard library only.\"\"\"\nimport json\nfrom fractions import Fraction\nN = 1\nobservations = []\ndef solve(state, nonref, ref, pct):\n    after = max(0, state - nonref)\n    local = int(state * Fraction(pct) / 100 + Fraction(1, 2))\n    return [local, after + local - ref]\ndef check(label, actual, expected):\n    observations.append({\"check\": label, \"actual\": actual, \"expected\": expected, \"passed\": actual == expected})\ncases = [[('regression surtax-base 1', (100000, 20000, 5000, '17.5'), [14000, 89000]),\n  ('regression surtax-base 2', (1000, 3000, 500, '20'), [0, -500]),\n  ('partial repair guard 2', (5000, 1000, 9000, '12.5'), [500, -4500]),\n  ('control: rounding', (333, 0, 0, '1.5'), [5, 338]), ('control: half cent', (1001, 0, 0, '50'), [501, 1502]),\n  ('control: no surtax', (4200, 100, 0, '0'), [0, 4100])],\n [('regression surtax-base 1', (5000, 1000, 9000, '12.5'), [500, -4500]),\n  ('regression surtax-base 2', (143686, 20000, 9000, '17.5'), [21645, 136331]),\n  ('partial repair guard 2', (86323, 79662, 500, '12.5'), [833, 6994]),\n  ('control: half cent', (1001, 0, 0, '50'), [501, 1502]), ('control: no surtax', (4200, 100, 0, '0'), [0, 4100]),\n  ('control: typical', (100000, 20000, 5000, '17.5'), [14000, 89000]),\n  ('control: credits exceed tax', (1000, 3000, 500, '20'), [0, -500])],\n [('regression surtax-base 1', (133783, 45064, 0, '17.5'), [15526, 104245]),\n  ('regression surtax-base 2', (27192, 1000, 0, '12.5'), [3274, 29466]),\n  ('partial repair guard 1', (44678, 28763, 500, '50'), [7958, 23373]),\n  ('partial repair guard 2', (176644, 20000, 500, '8'), [12532, 168676]),\n  ('control: typical', (100000, 20000, 5000, '17.5'), [14000, 89000]),\n  ('control: credits exceed tax', (1000, 3000, 500, '20'), [0, -500]),\n  ('control: rounding', (333, 0, 0, '1.5'), [5, 338]),\n  ('control: large refund', (5000, 1000, 9000, '12.5'), [500, -4500])],\n [('regression surtax-base 1', (86323, 79662, 500, '12.5'), [833, 6994]),\n  ('regression surtax-base 2', (44678, 28763, 500, '50'), [7958, 23373]),\n  ('partial repair guard 1', (107676, 1000, 9000, '8'), [8534, 106210]),\n  ('partial repair guard 2', (96269, 20000, 9000, '8'), [6102, 73371]),\n  ('control: large refund', (5000, 1000, 9000, '12.5'), [500, -4500]),\n  ('control: half cent', (1001, 0, 0, '50'), [501, 1502]), ('control: no surtax', (4200, 100, 0, '0'), [0, 4100]),\n  ('control: typical', (100000, 20000, 5000, '17.5'), [14000, 89000])],\n [('regression surtax-base 1', (176644, 20000, 500, '8'), [12532, 168676]),\n  ('regression surtax-base 2', (107676, 1000, 9000, '8'), [8534, 106210]),\n  ('partial repair guard 1', (171795, 55836, 500, '1.5'), [1739, 117198]),\n  ('partial repair guard 2', (195423, 1000, 9000, '17.5'), [34024, 219447]),\n  ('control: typical', (100000, 20000, 5000, '17.5'), [14000, 89000]),\n  ('control: credits exceed tax', (1000, 3000, 500, '20'), [0, -500]),\n  ('control: rounding', (333, 0, 0, '1.5'), [5, 338]),\n  ('control: large refund', (5000, 1000, 9000, '12.5'), [500, -4500])]]\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"},"fixed":{"sha256":"396edfdb804134d218ef5ebae16782c84d1355c6a43a26d3c4769357a0b513c6","source":"\"\"\"Failure Map reference implementation. Python standard library only.\"\"\"\nimport json\nfrom fractions import Fraction\nN = 1\nobservations = []\ndef solve(state, nonref, ref, pct):\n    after = max(0, state - nonref)\n    local = int(after * Fraction(pct) / 100 + Fraction(1, 2))\n    return [local, after + local - ref]\ndef check(label, actual, expected):\n    observations.append({\"check\": label, \"actual\": actual, \"expected\": expected, \"passed\": actual == expected})\ncases = [[('regression surtax-base 1', (100000, 20000, 5000, '17.5'), [14000, 89000]),\n  ('regression surtax-base 2', (1000, 3000, 500, '20'), [0, -500]),\n  ('partial repair guard 2', (5000, 1000, 9000, '12.5'), [500, -4500]),\n  ('control: rounding', (333, 0, 0, '1.5'), [5, 338]), ('control: half cent', (1001, 0, 0, '50'), [501, 1502]),\n  ('control: no surtax', (4200, 100, 0, '0'), [0, 4100])],\n [('regression surtax-base 1', (5000, 1000, 9000, '12.5'), [500, -4500]),\n  ('regression surtax-base 2', (143686, 20000, 9000, '17.5'), [21645, 136331]),\n  ('partial repair guard 2', (86323, 79662, 500, '12.5'), [833, 6994]),\n  ('control: half cent', (1001, 0, 0, '50'), [501, 1502]), ('control: no surtax', (4200, 100, 0, '0'), [0, 4100]),\n  ('control: typical', (100000, 20000, 5000, '17.5'), [14000, 89000]),\n  ('control: credits exceed tax', (1000, 3000, 500, '20'), [0, -500])],\n [('regression surtax-base 1', (133783, 45064, 0, '17.5'), [15526, 104245]),\n  ('regression surtax-base 2', (27192, 1000, 0, '12.5'), [3274, 29466]),\n  ('partial repair guard 1', (44678, 28763, 500, '50'), [7958, 23373]),\n  ('partial repair guard 2', (176644, 20000, 500, '8'), [12532, 168676]),\n  ('control: typical', (100000, 20000, 5000, '17.5'), [14000, 89000]),\n  ('control: credits exceed tax', (1000, 3000, 500, '20'), [0, -500]),\n  ('control: rounding', (333, 0, 0, '1.5'), [5, 338]),\n  ('control: large refund', (5000, 1000, 9000, '12.5'), [500, -4500])],\n [('regression surtax-base 1', (86323, 79662, 500, '12.5'), [833, 6994]),\n  ('regression surtax-base 2', (44678, 28763, 500, '50'), [7958, 23373]),\n  ('partial repair guard 1', (107676, 1000, 9000, '8'), [8534, 106210]),\n  ('partial repair guard 2', (96269, 20000, 9000, '8'), [6102, 73371]),\n  ('control: large refund', (5000, 1000, 9000, '12.5'), [500, -4500]),\n  ('control: half cent', (1001, 0, 0, '50'), [501, 1502]), ('control: no surtax', (4200, 100, 0, '0'), [0, 4100]),\n  ('control: typical', (100000, 20000, 5000, '17.5'), [14000, 89000])],\n [('regression surtax-base 1', (176644, 20000, 500, '8'), [12532, 168676]),\n  ('regression surtax-base 2', (107676, 1000, 9000, '8'), [8534, 106210]),\n  ('partial repair guard 1', (171795, 55836, 500, '1.5'), [1739, 117198]),\n  ('partial repair guard 2', (195423, 1000, 9000, '17.5'), [34024, 219447]),\n  ('control: typical', (100000, 20000, 5000, '17.5'), [14000, 89000]),\n  ('control: credits exceed tax', (1000, 3000, 500, '20'), [0, -500]),\n  ('control: rounding', (333, 0, 0, '1.5'), [5, 338]),\n  ('control: large refund', (5000, 1000, 9000, '12.5'), [500, -4500])]]\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-local-piggyback-surtax-surtax-base","generated_at":"2026-09-29T14:47:06.939203+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.","repair":"Base the surtax on state tax after nonrefundable credits.","root_cause":"The surtax base is the gross state tax.","sha256":"e9ea5f6a65f313c779c8c7bcdbbf2edafb665712e64265be9e03eebd424af0c6","title":"The local surtax is computed on state tax before credits · case 01","variant":1,"variant_policy":"Five numbered records share a model and may reuse boundary fixtures.","verification":{"attempt":{"elapsed_ms":45.163,"exit_code":1,"observations":[{"actual":[13125,88125],"check":"regression surtax-base 1","expected":[14000,89000],"passed":false},{"actual":[0,-500],"check":"regression surtax-base 2","expected":[0,-500],"passed":true},{"actual":[0,-5000],"check":"partial repair guard 2","expected":[500,-4500],"passed":false},{"actual":[5,338],"check":"control: rounding","expected":[5,338],"passed":true},{"actual":[501,1502],"check":"control: half cent","expected":[501,1502],"passed":true},{"actual":[0,4100],"check":"control: no surtax","expected":[0,4100],"passed":true}],"passed":false,"stderr":"","stdout":"{\"observations\": [{\"check\": \"regression surtax-base 1\", \"actual\": [13125, 88125], \"expected\": [14000, 89000], \"passed\": false}, {\"check\": \"regression surtax-base 2\", \"actual\": [0, -500], \"expected\": [0, -500], \"passed\": true}, {\"check\": \"partial repair guard 2\", \"actual\": [0, -5000], \"expected\": [500, -4500], \"passed\": false}, {\"check\": \"control: rounding\", \"actual\": [5, 338], \"expected\": [5, 338], \"passed\": true}, {\"check\": \"control: half cent\", \"actual\": [501, 1502], \"expected\": [501, 1502], \"passed\": true}, {\"check\": \"control: no surtax\", \"actual\": [0, 4100], \"expected\": [0, 4100], \"passed\": true}], \"passed\": false}\n"},"broken":{"elapsed_ms":44.947,"exit_code":1,"observations":[{"actual":[17500,92500],"check":"regression surtax-base 1","expected":[14000,89000],"passed":false},{"actual":[200,-300],"check":"regression surtax-base 2","expected":[0,-500],"passed":false},{"actual":[625,-4375],"check":"partial repair guard 2","expected":[500,-4500],"passed":false},{"actual":[5,338],"check":"control: rounding","expected":[5,338],"passed":true},{"actual":[501,1502],"check":"control: half cent","expected":[501,1502],"passed":true},{"actual":[0,4100],"check":"control: no surtax","expected":[0,4100],"passed":true}],"passed":false,"stderr":"","stdout":"{\"observations\": [{\"check\": \"regression surtax-base 1\", \"actual\": [17500, 92500], \"expected\": [14000, 89000], \"passed\": false}, {\"check\": \"regression surtax-base 2\", \"actual\": [200, -300], \"expected\": [0, -500], \"passed\": false}, {\"check\": \"partial repair guard 2\", \"actual\": [625, -4375], \"expected\": [500, -4500], \"passed\": false}, {\"check\": \"control: rounding\", \"actual\": [5, 338], \"expected\": [5, 338], \"passed\": true}, {\"check\": \"control: half cent\", \"actual\": [501, 1502], \"expected\": [501, 1502], \"passed\": true}, {\"check\": \"control: no surtax\", \"actual\": [0, 4100], \"expected\": [0, 4100], \"passed\": true}], \"passed\": false}\n"},"fixed":{"elapsed_ms":42.511,"exit_code":0,"observations":[{"actual":[14000,89000],"check":"regression surtax-base 1","expected":[14000,89000],"passed":true},{"actual":[0,-500],"check":"regression surtax-base 2","expected":[0,-500],"passed":true},{"actual":[500,-4500],"check":"partial repair guard 2","expected":[500,-4500],"passed":true},{"actual":[5,338],"check":"control: rounding","expected":[5,338],"passed":true},{"actual":[501,1502],"check":"control: half cent","expected":[501,1502],"passed":true},{"actual":[0,4100],"check":"control: no surtax","expected":[0,4100],"passed":true}],"passed":true,"stderr":"","stdout":"{\"observations\": [{\"check\": \"regression surtax-base 1\", \"actual\": [14000, 89000], \"expected\": [14000, 89000], \"passed\": true}, {\"check\": \"regression surtax-base 2\", \"actual\": [0, -500], \"expected\": [0, -500], \"passed\": true}, {\"check\": \"partial repair guard 2\", \"actual\": [500, -4500], \"expected\": [500, -4500], \"passed\": true}, {\"check\": \"control: rounding\", \"actual\": [5, 338], \"expected\": [5, 338], \"passed\": true}, {\"check\": \"control: half cent\", \"actual\": [501, 1502], \"expected\": [501, 1502], \"passed\": true}, {\"check\": \"control: no surtax\", \"actual\": [0, 4100], \"expected\": [0, 4100], \"passed\": true}], \"passed\": true}\n"}},"verified":true,"visibility":"public"}