{"abstract":"The fully earned acquisition fee is partly rebated.","category":"Loan amortization schedules","checks":7,"contract":"x = {'term' n, 'paid' k, 'finance_charge', 'acq_fee' (fully earned up front), 'payment', 'min_rebate'}. Rebatable charge = finance_charge - acq_fee; remaining r = n - k; rebate = round_half_up(rebatable * r(r+1) / (n(n+1))), set to 0 when below min_rebate. Payoff = payment*r - rebate; earned = finance_charge - rebate. Return {'rebate', 'payoff', 'earned'}.","evaluation_group":"w2-loan-amortization-schedules-rule-of-78-rebate","failed_approach":"Excluding only a prorated share of the fee still rebates part of it.","family":"w2-loan-amortization-schedules-rule-of-78-rebate-acquisition-fee-exclusion","id":"FA-58626","implementations":{"attempt":{"sha256":"66a4c442c33500de0c305b4ce1cd6d89c504e537bde5470f64ccde1e9f07c1d3","source":"\"\"\"Failure Map reference implementation. Python standard library only.\"\"\"\nimport json\n\nN = 1\nobservations = []\ndef solve(x):\n    def rnd(n, d):\n        q, r = divmod(n, d)\n        return q + (1 if 2 * r >= d else 0)\n    n = x['term']\n    k = x['paid']\n    fc = x['finance_charge'] - x['acq_fee'] * (n - k) // n\n    rem = n - k\n    rebate = rnd(fc * rem * (rem + 1), n * (n + 1))\n    if rebate < x['min_rebate']:\n        rebate = 0\n    remaining = x['payment'] * rem\n    return {'rebate': rebate, 'payoff': remaining - rebate, 'earned': x['finance_charge'] - rebate}\ndef check(label, actual, expected):\n    observations.append({\"check\": label, \"actual\": actual, \"expected\": expected, \"passed\": actual == expected})\nfixtures = [[['regression: acquisition fee exclusion', {'term': 36, 'paid': 18, 'finance_charge': 50000, 'acq_fee': 7500, 'payment': 25000, 'min_rebate': 100}, {'rebate': 10912, 'payoff': 439088, 'earned': 39088}], ['control 1', {'term': 36, 'paid': 35, 'finance_charge': 120000, 'acq_fee': 0, 'payment': 10000, 'min_rebate': 100}, {'rebate': 180, 'payoff': 9820, 'earned': 119820}], ['control 2', {'term': 36, 'paid': 35, 'finance_charge': 50000, 'acq_fee': 7500, 'payment': 25000, 'min_rebate': 100}, {'rebate': 0, 'payoff': 25000, 'earned': 50000}], ['control 3', {'term': 24, 'paid': 23, 'finance_charge': 100, 'acq_fee': 0, 'payment': 25000, 'min_rebate': 100}, {'rebate': 0, 'payoff': 25000, 'earned': 100}], ['control 4', {'term': 24, 'paid': 12, 'finance_charge': 50000, 'acq_fee': 0, 'payment': 25000, 'min_rebate': 100}, {'rebate': 13000, 'payoff': 287000, 'earned': 37000}], ['control 5', {'term': 12, 'paid': 3, 'finance_charge': 100, 'acq_fee': 0, 'payment': 4321, 'min_rebate': 100}, {'rebate': 0, 'payoff': 38889, 'earned': 100}], ['control 6', {'term': 6, 'paid': 3, 'finance_charge': 7777, 'acq_fee': 0, 'payment': 10000, 'min_rebate': 500}, {'rebate': 2222, 'payoff': 27778, 'earned': 5555}]], [['regression: acquisition fee exclusion', {'term': 36, 'paid': 3, 'finance_charge': 7777, 'acq_fee': 2500, 'payment': 10000, 'min_rebate': 500}, {'rebate': 4445, 'payoff': 325555, 'earned': 3332}], ['control 1', {'term': 24, 'paid': 1, 'finance_charge': 120000, 'acq_fee': 0, 'payment': 25000, 'min_rebate': 500}, {'rebate': 110400, 'payoff': 464600, 'earned': 9600}], ['control 2', {'term': 12, 'paid': 1, 'finance_charge': 100, 'acq_fee': 0, 'payment': 10000, 'min_rebate': 100}, {'rebate': 0, 'payoff': 110000, 'earned': 100}], ['control 3', {'term': 24, 'paid': 24, 'finance_charge': 120000, 'acq_fee': 0, 'payment': 10000, 'min_rebate': 100}, {'rebate': 0, 'payoff': 0, 'earned': 120000}], ['control 4', {'term': 36, 'paid': 0, 'finance_charge': 100, 'acq_fee': 7500, 'payment': 25000, 'min_rebate': 500}, {'rebate': 0, 'payoff': 900000, 'earned': 100}], ['control 5', {'term': 24, 'paid': 12, 'finance_charge': 100, 'acq_fee': 2500, 'payment': 10000, 'min_rebate': 500}, {'rebate': 0, 'payoff': 120000, 'earned': 100}], ['control 6', {'term': 6, 'paid': 0, 'finance_charge': 7777, 'acq_fee': 0, 'payment': 10000, 'min_rebate': 500}, {'rebate': 7777, 'payoff': 52223, 'earned': 0}]], [['regression: acquisition fee exclusion', {'term': 6, 'paid': 3, 'finance_charge': 7777, 'acq_fee': 7500, 'payment': 4321, 'min_rebate': 0}, {'rebate': 79, 'payoff': 12884, 'earned': 7698}], ['control 1', {'term': 6, 'paid': 5, 'finance_charge': 100, 'acq_fee': 0, 'payment': 25000, 'min_rebate': 2000}, {'rebate': 0, 'payoff': 25000, 'earned': 100}], ['control 2', {'term': 24, 'paid': 3, 'finance_charge': 120000, 'acq_fee': 0, 'payment': 10000, 'min_rebate': 2000}, {'rebate': 92400, 'payoff': 117600, 'earned': 27600}], ['control 3', {'term': 12, 'paid': 3, 'finance_charge': 50000, 'acq_fee': 0, 'payment': 4321, 'min_rebate': 2000}, {'rebate': 28846, 'payoff': 10043, 'earned': 21154}], ['control 4', {'term': 6, 'paid': 5, 'finance_charge': 120000, 'acq_fee': 0, 'payment': 10000, 'min_rebate': 0}, {'rebate': 5714, 'payoff': 4286, 'earned': 114286}], ['control 5', {'term': 12, 'paid': 12, 'finance_charge': 7777, 'acq_fee': 7500, 'payment': 10000, 'min_rebate': 2000}, {'rebate': 0, 'payoff': 0, 'earned': 7777}], ['control 6', {'term': 24, 'paid': 24, 'finance_charge': 7777, 'acq_fee': 7500, 'payment': 10000, 'min_rebate': 0}, {'rebate': 0, 'payoff': 0, 'earned': 7777}]], [['regression: acquisition fee exclusion', {'term': 24, 'paid': 12, 'finance_charge': 120000, 'acq_fee': 2500, 'payment': 4321, 'min_rebate': 100}, {'rebate': 30550, 'payoff': 21302, 'earned': 89450}], ['control 1', {'term': 36, 'paid': 0, 'finance_charge': 100, 'acq_fee': 7500, 'payment': 25000, 'min_rebate': 500}, {'rebate': 0, 'payoff': 900000, 'earned': 100}], ['control 2', {'term': 12, 'paid': 12, 'finance_charge': 50000, 'acq_fee': 2500, 'payment': 10000, 'min_rebate': 0}, {'rebate': 0, 'payoff': 0, 'earned': 50000}], ['control 3', {'term': 12, 'paid': 0, 'finance_charge': 7777, 'acq_fee': 0, 'payment': 4321, 'min_rebate': 2000}, {'rebate': 7777, 'payoff': 44075, 'earned': 0}], ['control 4', {'term': 36, 'paid': 0, 'finance_charge': 100, 'acq_fee': 0, 'payment': 10000, 'min_rebate': 0}, {'rebate': 100, 'payoff': 359900, 'earned': 0}], ['control 5', {'term': 6, 'paid': 3, 'finance_charge': 100, 'acq_fee': 0, 'payment': 25000, 'min_rebate': 2000}, {'rebate': 0, 'payoff': 75000, 'earned': 100}], ['control 6', {'term': 36, 'paid': 18, 'finance_charge': 50000, 'acq_fee': 0, 'payment': 4321, 'min_rebate': 0}, {'rebate': 12838, 'payoff': 64940, 'earned': 37162}]], [['regression: acquisition fee exclusion', {'term': 24, 'paid': 12, 'finance_charge': 120000, 'acq_fee': 7500, 'payment': 25000, 'min_rebate': 500}, {'rebate': 29250, 'payoff': 270750, 'earned': 90750}], ['control 1', {'term': 24, 'paid': 12, 'finance_charge': 100, 'acq_fee': 0, 'payment': 4321, 'min_rebate': 500}, {'rebate': 0, 'payoff': 51852, 'earned': 100}], ['control 2', {'term': 36, 'paid': 36, 'finance_charge': 100, 'acq_fee': 7500, 'payment': 4321, 'min_rebate': 0}, {'rebate': 0, 'payoff': 0, 'earned': 100}], ['control 3', {'term': 12, 'paid': 0, 'finance_charge': 100, 'acq_fee': 0, 'payment': 25000, 'min_rebate': 500}, {'rebate': 0, 'payoff': 300000, 'earned': 100}], ['control 4', {'term': 12, 'paid': 12, 'finance_charge': 7777, 'acq_fee': 0, 'payment': 10000, 'min_rebate': 2000}, {'rebate': 0, 'payoff': 0, 'earned': 7777}], ['control 5', {'term': 24, 'paid': 0, 'finance_charge': 100, 'acq_fee': 0, 'payment': 4321, 'min_rebate': 0}, {'rebate': 100, 'payoff': 103604, 'earned': 0}], ['control 6', {'term': 6, 'paid': 5, 'finance_charge': 100, 'acq_fee': 7500, 'payment': 4321, 'min_rebate': 100}, {'rebate': 0, 'payoff': 4321, 'earned': 100}]]]\nfor label, args, expected in fixtures[N-1]:\n    try:\n        actual = solve(args)\n    except Exception as exc:\n        actual = 'raised ' + type(exc).__name__\n    check(label, actual, 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":"b3bc6de18c4a5f0e6f24653a7466540197de4f31e9b26feb589dc15b7272dbd2","source":"\"\"\"Failure Map reference implementation. Python standard library only.\"\"\"\nimport json\n\nN = 1\nobservations = []\ndef solve(x):\n    def rnd(n, d):\n        q, r = divmod(n, d)\n        return q + (1 if 2 * r >= d else 0)\n    n = x['term']\n    k = x['paid']\n    fc = x['finance_charge']\n    rem = n - k\n    rebate = rnd(fc * rem * (rem + 1), n * (n + 1))\n    if rebate < x['min_rebate']:\n        rebate = 0\n    remaining = x['payment'] * rem\n    return {'rebate': rebate, 'payoff': remaining - rebate, 'earned': x['finance_charge'] - rebate}\ndef check(label, actual, expected):\n    observations.append({\"check\": label, \"actual\": actual, \"expected\": expected, \"passed\": actual == expected})\nfixtures = [[['regression: acquisition fee exclusion', {'term': 36, 'paid': 18, 'finance_charge': 50000, 'acq_fee': 7500, 'payment': 25000, 'min_rebate': 100}, {'rebate': 10912, 'payoff': 439088, 'earned': 39088}], ['control 1', {'term': 36, 'paid': 35, 'finance_charge': 120000, 'acq_fee': 0, 'payment': 10000, 'min_rebate': 100}, {'rebate': 180, 'payoff': 9820, 'earned': 119820}], ['control 2', {'term': 36, 'paid': 35, 'finance_charge': 50000, 'acq_fee': 7500, 'payment': 25000, 'min_rebate': 100}, {'rebate': 0, 'payoff': 25000, 'earned': 50000}], ['control 3', {'term': 24, 'paid': 23, 'finance_charge': 100, 'acq_fee': 0, 'payment': 25000, 'min_rebate': 100}, {'rebate': 0, 'payoff': 25000, 'earned': 100}], ['control 4', {'term': 24, 'paid': 12, 'finance_charge': 50000, 'acq_fee': 0, 'payment': 25000, 'min_rebate': 100}, {'rebate': 13000, 'payoff': 287000, 'earned': 37000}], ['control 5', {'term': 12, 'paid': 3, 'finance_charge': 100, 'acq_fee': 0, 'payment': 4321, 'min_rebate': 100}, {'rebate': 0, 'payoff': 38889, 'earned': 100}], ['control 6', {'term': 6, 'paid': 3, 'finance_charge': 7777, 'acq_fee': 0, 'payment': 10000, 'min_rebate': 500}, {'rebate': 2222, 'payoff': 27778, 'earned': 5555}]], [['regression: acquisition fee exclusion', {'term': 36, 'paid': 3, 'finance_charge': 7777, 'acq_fee': 2500, 'payment': 10000, 'min_rebate': 500}, {'rebate': 4445, 'payoff': 325555, 'earned': 3332}], ['control 1', {'term': 24, 'paid': 1, 'finance_charge': 120000, 'acq_fee': 0, 'payment': 25000, 'min_rebate': 500}, {'rebate': 110400, 'payoff': 464600, 'earned': 9600}], ['control 2', {'term': 12, 'paid': 1, 'finance_charge': 100, 'acq_fee': 0, 'payment': 10000, 'min_rebate': 100}, {'rebate': 0, 'payoff': 110000, 'earned': 100}], ['control 3', {'term': 24, 'paid': 24, 'finance_charge': 120000, 'acq_fee': 0, 'payment': 10000, 'min_rebate': 100}, {'rebate': 0, 'payoff': 0, 'earned': 120000}], ['control 4', {'term': 36, 'paid': 0, 'finance_charge': 100, 'acq_fee': 7500, 'payment': 25000, 'min_rebate': 500}, {'rebate': 0, 'payoff': 900000, 'earned': 100}], ['control 5', {'term': 24, 'paid': 12, 'finance_charge': 100, 'acq_fee': 2500, 'payment': 10000, 'min_rebate': 500}, {'rebate': 0, 'payoff': 120000, 'earned': 100}], ['control 6', {'term': 6, 'paid': 0, 'finance_charge': 7777, 'acq_fee': 0, 'payment': 10000, 'min_rebate': 500}, {'rebate': 7777, 'payoff': 52223, 'earned': 0}]], [['regression: acquisition fee exclusion', {'term': 6, 'paid': 3, 'finance_charge': 7777, 'acq_fee': 7500, 'payment': 4321, 'min_rebate': 0}, {'rebate': 79, 'payoff': 12884, 'earned': 7698}], ['control 1', {'term': 6, 'paid': 5, 'finance_charge': 100, 'acq_fee': 0, 'payment': 25000, 'min_rebate': 2000}, {'rebate': 0, 'payoff': 25000, 'earned': 100}], ['control 2', {'term': 24, 'paid': 3, 'finance_charge': 120000, 'acq_fee': 0, 'payment': 10000, 'min_rebate': 2000}, {'rebate': 92400, 'payoff': 117600, 'earned': 27600}], ['control 3', {'term': 12, 'paid': 3, 'finance_charge': 50000, 'acq_fee': 0, 'payment': 4321, 'min_rebate': 2000}, {'rebate': 28846, 'payoff': 10043, 'earned': 21154}], ['control 4', {'term': 6, 'paid': 5, 'finance_charge': 120000, 'acq_fee': 0, 'payment': 10000, 'min_rebate': 0}, {'rebate': 5714, 'payoff': 4286, 'earned': 114286}], ['control 5', {'term': 12, 'paid': 12, 'finance_charge': 7777, 'acq_fee': 7500, 'payment': 10000, 'min_rebate': 2000}, {'rebate': 0, 'payoff': 0, 'earned': 7777}], ['control 6', {'term': 24, 'paid': 24, 'finance_charge': 7777, 'acq_fee': 7500, 'payment': 10000, 'min_rebate': 0}, {'rebate': 0, 'payoff': 0, 'earned': 7777}]], [['regression: acquisition fee exclusion', {'term': 24, 'paid': 12, 'finance_charge': 120000, 'acq_fee': 2500, 'payment': 4321, 'min_rebate': 100}, {'rebate': 30550, 'payoff': 21302, 'earned': 89450}], ['control 1', {'term': 36, 'paid': 0, 'finance_charge': 100, 'acq_fee': 7500, 'payment': 25000, 'min_rebate': 500}, {'rebate': 0, 'payoff': 900000, 'earned': 100}], ['control 2', {'term': 12, 'paid': 12, 'finance_charge': 50000, 'acq_fee': 2500, 'payment': 10000, 'min_rebate': 0}, {'rebate': 0, 'payoff': 0, 'earned': 50000}], ['control 3', {'term': 12, 'paid': 0, 'finance_charge': 7777, 'acq_fee': 0, 'payment': 4321, 'min_rebate': 2000}, {'rebate': 7777, 'payoff': 44075, 'earned': 0}], ['control 4', {'term': 36, 'paid': 0, 'finance_charge': 100, 'acq_fee': 0, 'payment': 10000, 'min_rebate': 0}, {'rebate': 100, 'payoff': 359900, 'earned': 0}], ['control 5', {'term': 6, 'paid': 3, 'finance_charge': 100, 'acq_fee': 0, 'payment': 25000, 'min_rebate': 2000}, {'rebate': 0, 'payoff': 75000, 'earned': 100}], ['control 6', {'term': 36, 'paid': 18, 'finance_charge': 50000, 'acq_fee': 0, 'payment': 4321, 'min_rebate': 0}, {'rebate': 12838, 'payoff': 64940, 'earned': 37162}]], [['regression: acquisition fee exclusion', {'term': 24, 'paid': 12, 'finance_charge': 120000, 'acq_fee': 7500, 'payment': 25000, 'min_rebate': 500}, {'rebate': 29250, 'payoff': 270750, 'earned': 90750}], ['control 1', {'term': 24, 'paid': 12, 'finance_charge': 100, 'acq_fee': 0, 'payment': 4321, 'min_rebate': 500}, {'rebate': 0, 'payoff': 51852, 'earned': 100}], ['control 2', {'term': 36, 'paid': 36, 'finance_charge': 100, 'acq_fee': 7500, 'payment': 4321, 'min_rebate': 0}, {'rebate': 0, 'payoff': 0, 'earned': 100}], ['control 3', {'term': 12, 'paid': 0, 'finance_charge': 100, 'acq_fee': 0, 'payment': 25000, 'min_rebate': 500}, {'rebate': 0, 'payoff': 300000, 'earned': 100}], ['control 4', {'term': 12, 'paid': 12, 'finance_charge': 7777, 'acq_fee': 0, 'payment': 10000, 'min_rebate': 2000}, {'rebate': 0, 'payoff': 0, 'earned': 7777}], ['control 5', {'term': 24, 'paid': 0, 'finance_charge': 100, 'acq_fee': 0, 'payment': 4321, 'min_rebate': 0}, {'rebate': 100, 'payoff': 103604, 'earned': 0}], ['control 6', {'term': 6, 'paid': 5, 'finance_charge': 100, 'acq_fee': 7500, 'payment': 4321, 'min_rebate': 100}, {'rebate': 0, 'payoff': 4321, 'earned': 100}]]]\nfor label, args, expected in fixtures[N-1]:\n    try:\n        actual = solve(args)\n    except Exception as exc:\n        actual = 'raised ' + type(exc).__name__\n    check(label, actual, 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":"2151e4b33294bcdf616d039c74cae2c9136e6a13427110c4e9d25fdcbf538949","source":"\"\"\"Failure Map reference implementation. Python standard library only.\"\"\"\nimport json\n\nN = 1\nobservations = []\ndef solve(x):\n    def rnd(n, d):\n        q, r = divmod(n, d)\n        return q + (1 if 2 * r >= d else 0)\n    n = x['term']\n    k = x['paid']\n    fc = x['finance_charge'] - x['acq_fee']\n    rem = n - k\n    rebate = rnd(fc * rem * (rem + 1), n * (n + 1))\n    if rebate < x['min_rebate']:\n        rebate = 0\n    remaining = x['payment'] * rem\n    return {'rebate': rebate, 'payoff': remaining - rebate, 'earned': x['finance_charge'] - rebate}\ndef check(label, actual, expected):\n    observations.append({\"check\": label, \"actual\": actual, \"expected\": expected, \"passed\": actual == expected})\nfixtures = [[['regression: acquisition fee exclusion', {'term': 36, 'paid': 18, 'finance_charge': 50000, 'acq_fee': 7500, 'payment': 25000, 'min_rebate': 100}, {'rebate': 10912, 'payoff': 439088, 'earned': 39088}], ['control 1', {'term': 36, 'paid': 35, 'finance_charge': 120000, 'acq_fee': 0, 'payment': 10000, 'min_rebate': 100}, {'rebate': 180, 'payoff': 9820, 'earned': 119820}], ['control 2', {'term': 36, 'paid': 35, 'finance_charge': 50000, 'acq_fee': 7500, 'payment': 25000, 'min_rebate': 100}, {'rebate': 0, 'payoff': 25000, 'earned': 50000}], ['control 3', {'term': 24, 'paid': 23, 'finance_charge': 100, 'acq_fee': 0, 'payment': 25000, 'min_rebate': 100}, {'rebate': 0, 'payoff': 25000, 'earned': 100}], ['control 4', {'term': 24, 'paid': 12, 'finance_charge': 50000, 'acq_fee': 0, 'payment': 25000, 'min_rebate': 100}, {'rebate': 13000, 'payoff': 287000, 'earned': 37000}], ['control 5', {'term': 12, 'paid': 3, 'finance_charge': 100, 'acq_fee': 0, 'payment': 4321, 'min_rebate': 100}, {'rebate': 0, 'payoff': 38889, 'earned': 100}], ['control 6', {'term': 6, 'paid': 3, 'finance_charge': 7777, 'acq_fee': 0, 'payment': 10000, 'min_rebate': 500}, {'rebate': 2222, 'payoff': 27778, 'earned': 5555}]], [['regression: acquisition fee exclusion', {'term': 36, 'paid': 3, 'finance_charge': 7777, 'acq_fee': 2500, 'payment': 10000, 'min_rebate': 500}, {'rebate': 4445, 'payoff': 325555, 'earned': 3332}], ['control 1', {'term': 24, 'paid': 1, 'finance_charge': 120000, 'acq_fee': 0, 'payment': 25000, 'min_rebate': 500}, {'rebate': 110400, 'payoff': 464600, 'earned': 9600}], ['control 2', {'term': 12, 'paid': 1, 'finance_charge': 100, 'acq_fee': 0, 'payment': 10000, 'min_rebate': 100}, {'rebate': 0, 'payoff': 110000, 'earned': 100}], ['control 3', {'term': 24, 'paid': 24, 'finance_charge': 120000, 'acq_fee': 0, 'payment': 10000, 'min_rebate': 100}, {'rebate': 0, 'payoff': 0, 'earned': 120000}], ['control 4', {'term': 36, 'paid': 0, 'finance_charge': 100, 'acq_fee': 7500, 'payment': 25000, 'min_rebate': 500}, {'rebate': 0, 'payoff': 900000, 'earned': 100}], ['control 5', {'term': 24, 'paid': 12, 'finance_charge': 100, 'acq_fee': 2500, 'payment': 10000, 'min_rebate': 500}, {'rebate': 0, 'payoff': 120000, 'earned': 100}], ['control 6', {'term': 6, 'paid': 0, 'finance_charge': 7777, 'acq_fee': 0, 'payment': 10000, 'min_rebate': 500}, {'rebate': 7777, 'payoff': 52223, 'earned': 0}]], [['regression: acquisition fee exclusion', {'term': 6, 'paid': 3, 'finance_charge': 7777, 'acq_fee': 7500, 'payment': 4321, 'min_rebate': 0}, {'rebate': 79, 'payoff': 12884, 'earned': 7698}], ['control 1', {'term': 6, 'paid': 5, 'finance_charge': 100, 'acq_fee': 0, 'payment': 25000, 'min_rebate': 2000}, {'rebate': 0, 'payoff': 25000, 'earned': 100}], ['control 2', {'term': 24, 'paid': 3, 'finance_charge': 120000, 'acq_fee': 0, 'payment': 10000, 'min_rebate': 2000}, {'rebate': 92400, 'payoff': 117600, 'earned': 27600}], ['control 3', {'term': 12, 'paid': 3, 'finance_charge': 50000, 'acq_fee': 0, 'payment': 4321, 'min_rebate': 2000}, {'rebate': 28846, 'payoff': 10043, 'earned': 21154}], ['control 4', {'term': 6, 'paid': 5, 'finance_charge': 120000, 'acq_fee': 0, 'payment': 10000, 'min_rebate': 0}, {'rebate': 5714, 'payoff': 4286, 'earned': 114286}], ['control 5', {'term': 12, 'paid': 12, 'finance_charge': 7777, 'acq_fee': 7500, 'payment': 10000, 'min_rebate': 2000}, {'rebate': 0, 'payoff': 0, 'earned': 7777}], ['control 6', {'term': 24, 'paid': 24, 'finance_charge': 7777, 'acq_fee': 7500, 'payment': 10000, 'min_rebate': 0}, {'rebate': 0, 'payoff': 0, 'earned': 7777}]], [['regression: acquisition fee exclusion', {'term': 24, 'paid': 12, 'finance_charge': 120000, 'acq_fee': 2500, 'payment': 4321, 'min_rebate': 100}, {'rebate': 30550, 'payoff': 21302, 'earned': 89450}], ['control 1', {'term': 36, 'paid': 0, 'finance_charge': 100, 'acq_fee': 7500, 'payment': 25000, 'min_rebate': 500}, {'rebate': 0, 'payoff': 900000, 'earned': 100}], ['control 2', {'term': 12, 'paid': 12, 'finance_charge': 50000, 'acq_fee': 2500, 'payment': 10000, 'min_rebate': 0}, {'rebate': 0, 'payoff': 0, 'earned': 50000}], ['control 3', {'term': 12, 'paid': 0, 'finance_charge': 7777, 'acq_fee': 0, 'payment': 4321, 'min_rebate': 2000}, {'rebate': 7777, 'payoff': 44075, 'earned': 0}], ['control 4', {'term': 36, 'paid': 0, 'finance_charge': 100, 'acq_fee': 0, 'payment': 10000, 'min_rebate': 0}, {'rebate': 100, 'payoff': 359900, 'earned': 0}], ['control 5', {'term': 6, 'paid': 3, 'finance_charge': 100, 'acq_fee': 0, 'payment': 25000, 'min_rebate': 2000}, {'rebate': 0, 'payoff': 75000, 'earned': 100}], ['control 6', {'term': 36, 'paid': 18, 'finance_charge': 50000, 'acq_fee': 0, 'payment': 4321, 'min_rebate': 0}, {'rebate': 12838, 'payoff': 64940, 'earned': 37162}]], [['regression: acquisition fee exclusion', {'term': 24, 'paid': 12, 'finance_charge': 120000, 'acq_fee': 7500, 'payment': 25000, 'min_rebate': 500}, {'rebate': 29250, 'payoff': 270750, 'earned': 90750}], ['control 1', {'term': 24, 'paid': 12, 'finance_charge': 100, 'acq_fee': 0, 'payment': 4321, 'min_rebate': 500}, {'rebate': 0, 'payoff': 51852, 'earned': 100}], ['control 2', {'term': 36, 'paid': 36, 'finance_charge': 100, 'acq_fee': 7500, 'payment': 4321, 'min_rebate': 0}, {'rebate': 0, 'payoff': 0, 'earned': 100}], ['control 3', {'term': 12, 'paid': 0, 'finance_charge': 100, 'acq_fee': 0, 'payment': 25000, 'min_rebate': 500}, {'rebate': 0, 'payoff': 300000, 'earned': 100}], ['control 4', {'term': 12, 'paid': 12, 'finance_charge': 7777, 'acq_fee': 0, 'payment': 10000, 'min_rebate': 2000}, {'rebate': 0, 'payoff': 0, 'earned': 7777}], ['control 5', {'term': 24, 'paid': 0, 'finance_charge': 100, 'acq_fee': 0, 'payment': 4321, 'min_rebate': 0}, {'rebate': 100, 'payoff': 103604, 'earned': 0}], ['control 6', {'term': 6, 'paid': 5, 'finance_charge': 100, 'acq_fee': 7500, 'payment': 4321, 'min_rebate': 100}, {'rebate': 0, 'payoff': 4321, 'earned': 100}]]]\nfor label, args, expected in fixtures[N-1]:\n    try:\n        actual = solve(args)\n    except Exception as exc:\n        actual = 'raised ' + type(exc).__name__\n    check(label, actual, 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 stipulated toy lending rules stated in the contract; money is integer cents and rates are basis points; it makes no claim of conformance to any regulation, servicing standard or product. 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-loan-amortization-schedules-rule-of-78-rebate-acquisition-fee-exclusion","generated_at":"2026-09-29T14:46:28.510550+00:00","license":"CC0-1.0","python":"3.12.14","seed":1,"split":"open-access"},"relevance":"Amortization engines drive borrower statements, payoff quotes and investor remittances; a misplaced rounding step, boundary or ordering rule compounds across hundreds of periods.","repair":"Exclude the acquisition fee from the rebatable charge.","root_cause":"The rebate base includes the acquisition fee.","sha256":"1ace4b036469e510950c17a8a2fa45b3594e362baf8eb93a1ce95e8349f2db62","title":"Rule of 78s early payoff rebate: acquisition fee exclusion · case 01","variant":1,"variant_policy":"Five numbered records share a model and may reuse boundary fixtures.","verification":{"attempt":{"elapsed_ms":39.476,"exit_code":1,"observations":[{"actual":{"earned":38125,"payoff":438125,"rebate":11875},"check":"regression: acquisition fee exclusion","expected":{"earned":39088,"payoff":439088,"rebate":10912},"passed":false},{"actual":{"earned":119820,"payoff":9820,"rebate":180},"check":"control 1","expected":{"earned":119820,"payoff":9820,"rebate":180},"passed":true},{"actual":{"earned":50000,"payoff":25000,"rebate":0},"check":"control 2","expected":{"earned":50000,"payoff":25000,"rebate":0},"passed":true},{"actual":{"earned":100,"payoff":25000,"rebate":0},"check":"control 3","expected":{"earned":100,"payoff":25000,"rebate":0},"passed":true},{"actual":{"earned":37000,"payoff":287000,"rebate":13000},"check":"control 4","expected":{"earned":37000,"payoff":287000,"rebate":13000},"passed":true},{"actual":{"earned":100,"payoff":38889,"rebate":0},"check":"control 5","expected":{"earned":100,"payoff":38889,"rebate":0},"passed":true},{"actual":{"earned":5555,"payoff":27778,"rebate":2222},"check":"control 6","expected":{"earned":5555,"payoff":27778,"rebate":2222},"passed":true}],"passed":false,"stderr":"","stdout":"{\"observations\": [{\"check\": \"regression: acquisition fee exclusion\", \"actual\": {\"rebate\": 11875, \"payoff\": 438125, \"earned\": 38125}, \"expected\": {\"rebate\": 10912, \"payoff\": 439088, \"earned\": 39088}, \"passed\": false}, {\"check\": \"control 1\", \"actual\": {\"rebate\": 180, \"payoff\": 9820, \"earned\": 119820}, \"expected\": {\"rebate\": 180, \"payoff\": 9820, \"earned\": 119820}, \"passed\": true}, {\"check\": \"control 2\", \"actual\": {\"rebate\": 0, \"payoff\": 25000, \"earned\": 50000}, \"expected\": {\"rebate\": 0, \"payoff\": 25000, \"earned\": 50000}, \"passed\": true}, {\"check\": \"control 3\", \"actual\": {\"rebate\": 0, \"payoff\": 25000, \"earned\": 100}, \"expected\": {\"rebate\": 0, \"payoff\": 25000, \"earned\": 100}, \"passed\": true}, {\"check\": \"control 4\", \"actual\": {\"rebate\": 13000, \"payoff\": 287000, \"earned\": 37000}, \"expected\": {\"rebate\": 13000, \"payoff\": 287000, \"earned\": 37000}, \"passed\": true}, {\"check\": \"control 5\", \"actual\": {\"rebate\": 0, \"payoff\": 38889, \"earned\": 100}, \"expected\": {\"rebate\": 0, \"payoff\": 38889, \"earned\": 100}, \"passed\": true}, {\"check\": \"control 6\", \"actual\": {\"rebate\": 2222, \"payoff\": 27778, \"earned\": 5555}, \"expected\": {\"rebate\": 2222, \"payoff\": 27778, \"earned\": 5555}, \"passed\": true}], \"passed\": false}\n"},"broken":{"elapsed_ms":39.693,"exit_code":1,"observations":[{"actual":{"earned":37162,"payoff":437162,"rebate":12838},"check":"regression: acquisition fee exclusion","expected":{"earned":39088,"payoff":439088,"rebate":10912},"passed":false},{"actual":{"earned":119820,"payoff":9820,"rebate":180},"check":"control 1","expected":{"earned":119820,"payoff":9820,"rebate":180},"passed":true},{"actual":{"earned":50000,"payoff":25000,"rebate":0},"check":"control 2","expected":{"earned":50000,"payoff":25000,"rebate":0},"passed":true},{"actual":{"earned":100,"payoff":25000,"rebate":0},"check":"control 3","expected":{"earned":100,"payoff":25000,"rebate":0},"passed":true},{"actual":{"earned":37000,"payoff":287000,"rebate":13000},"check":"control 4","expected":{"earned":37000,"payoff":287000,"rebate":13000},"passed":true},{"actual":{"earned":100,"payoff":38889,"rebate":0},"check":"control 5","expected":{"earned":100,"payoff":38889,"rebate":0},"passed":true},{"actual":{"earned":5555,"payoff":27778,"rebate":2222},"check":"control 6","expected":{"earned":5555,"payoff":27778,"rebate":2222},"passed":true}],"passed":false,"stderr":"","stdout":"{\"observations\": [{\"check\": \"regression: acquisition fee exclusion\", \"actual\": {\"rebate\": 12838, \"payoff\": 437162, \"earned\": 37162}, \"expected\": {\"rebate\": 10912, \"payoff\": 439088, \"earned\": 39088}, \"passed\": false}, {\"check\": \"control 1\", \"actual\": {\"rebate\": 180, \"payoff\": 9820, \"earned\": 119820}, \"expected\": {\"rebate\": 180, \"payoff\": 9820, \"earned\": 119820}, \"passed\": true}, {\"check\": \"control 2\", \"actual\": {\"rebate\": 0, \"payoff\": 25000, \"earned\": 50000}, \"expected\": {\"rebate\": 0, \"payoff\": 25000, \"earned\": 50000}, \"passed\": true}, {\"check\": \"control 3\", \"actual\": {\"rebate\": 0, \"payoff\": 25000, \"earned\": 100}, \"expected\": {\"rebate\": 0, \"payoff\": 25000, \"earned\": 100}, \"passed\": true}, {\"check\": \"control 4\", \"actual\": {\"rebate\": 13000, \"payoff\": 287000, \"earned\": 37000}, \"expected\": {\"rebate\": 13000, \"payoff\": 287000, \"earned\": 37000}, \"passed\": true}, {\"check\": \"control 5\", \"actual\": {\"rebate\": 0, \"payoff\": 38889, \"earned\": 100}, \"expected\": {\"rebate\": 0, \"payoff\": 38889, \"earned\": 100}, \"passed\": true}, {\"check\": \"control 6\", \"actual\": {\"rebate\": 2222, \"payoff\": 27778, \"earned\": 5555}, \"expected\": {\"rebate\": 2222, \"payoff\": 27778, \"earned\": 5555}, \"passed\": true}], \"passed\": false}\n"},"fixed":{"elapsed_ms":40.488,"exit_code":0,"observations":[{"actual":{"earned":39088,"payoff":439088,"rebate":10912},"check":"regression: acquisition fee exclusion","expected":{"earned":39088,"payoff":439088,"rebate":10912},"passed":true},{"actual":{"earned":119820,"payoff":9820,"rebate":180},"check":"control 1","expected":{"earned":119820,"payoff":9820,"rebate":180},"passed":true},{"actual":{"earned":50000,"payoff":25000,"rebate":0},"check":"control 2","expected":{"earned":50000,"payoff":25000,"rebate":0},"passed":true},{"actual":{"earned":100,"payoff":25000,"rebate":0},"check":"control 3","expected":{"earned":100,"payoff":25000,"rebate":0},"passed":true},{"actual":{"earned":37000,"payoff":287000,"rebate":13000},"check":"control 4","expected":{"earned":37000,"payoff":287000,"rebate":13000},"passed":true},{"actual":{"earned":100,"payoff":38889,"rebate":0},"check":"control 5","expected":{"earned":100,"payoff":38889,"rebate":0},"passed":true},{"actual":{"earned":5555,"payoff":27778,"rebate":2222},"check":"control 6","expected":{"earned":5555,"payoff":27778,"rebate":2222},"passed":true}],"passed":true,"stderr":"","stdout":"{\"observations\": [{\"check\": \"regression: acquisition fee exclusion\", \"actual\": {\"rebate\": 10912, \"payoff\": 439088, \"earned\": 39088}, \"expected\": {\"rebate\": 10912, \"payoff\": 439088, \"earned\": 39088}, \"passed\": true}, {\"check\": \"control 1\", \"actual\": {\"rebate\": 180, \"payoff\": 9820, \"earned\": 119820}, \"expected\": {\"rebate\": 180, \"payoff\": 9820, \"earned\": 119820}, \"passed\": true}, {\"check\": \"control 2\", \"actual\": {\"rebate\": 0, \"payoff\": 25000, \"earned\": 50000}, \"expected\": {\"rebate\": 0, \"payoff\": 25000, \"earned\": 50000}, \"passed\": true}, {\"check\": \"control 3\", \"actual\": {\"rebate\": 0, \"payoff\": 25000, \"earned\": 100}, \"expected\": {\"rebate\": 0, \"payoff\": 25000, \"earned\": 100}, \"passed\": true}, {\"check\": \"control 4\", \"actual\": {\"rebate\": 13000, \"payoff\": 287000, \"earned\": 37000}, \"expected\": {\"rebate\": 13000, \"payoff\": 287000, \"earned\": 37000}, \"passed\": true}, {\"check\": \"control 5\", \"actual\": {\"rebate\": 0, \"payoff\": 38889, \"earned\": 100}, \"expected\": {\"rebate\": 0, \"payoff\": 38889, \"earned\": 100}, \"passed\": true}, {\"check\": \"control 6\", \"actual\": {\"rebate\": 2222, \"payoff\": 27778, \"earned\": 5555}, \"expected\": {\"rebate\": 2222, \"payoff\": 27778, \"earned\": 5555}, \"passed\": true}], \"passed\": true}\n"}},"verified":true,"visibility":"public"}