Understand the failure.
Verify the repair.
Small, reproducible software failures. The broken implementation, the fix that didn’t work, and the one that passed—preserved together.
Explore the cases ↓How results are verified ↗WHAT THE ARCHIVE CONTAINS
100840 executable cases. 20168 are open.
Every case records the implementation that fails, the fix that did not work, and the repair that passed its checks—with recorded outputs and source hashes. This release adds 100840 cases across 20168 failure mechanisms and 254 domains.
The open tier gives you the failure and the unsuccessful fix for one case in every mechanism. The remaining 80672 cases, 5 variants per mechanism, are member-only: the verified repair, its recorded checks, and the full fixture suite are held in the member archive. Read the methodology ↗
A RECORD OF WHAT WENT WRONG
Browse the archive / 100840
Refundable credits are limited to the combined tax · case 01
Filers entitled to a refund receive zero.
Refundable credits are limited to the combined tax · case 02
Filers entitled to a refund receive zero.
Refundable credits are limited to the combined tax · case 03
Filers entitled to a refund receive zero.
Refundable credits are limited to the combined tax · case 04
Filers entitled to a refund receive zero.
Refundable credits are limited to the combined tax · case 05
Filers entitled to a refund receive zero.
The dividend tax credit is computed on the cash dividend instead of the grossed-up amount · case 01
Dividend recipients receive a smaller credit than the integration rules provide.
The dividend tax credit is computed on the cash dividend instead of the grossed-up amount · case 02
Dividend recipients receive a smaller credit than the integration rules provide.
The dividend tax credit is computed on the cash dividend instead of the grossed-up amount · case 03
Dividend recipients receive a smaller credit than the integration rules provide.
The dividend tax credit is computed on the cash dividend instead of the grossed-up amount · case 04
Dividend recipients receive a smaller credit than the integration rules provide.
The dividend tax credit is computed on the cash dividend instead of the grossed-up amount · case 05
Dividend recipients receive a smaller credit than the integration rules provide.
Eligible and non-eligible gross-up rates are swapped · case 01
Eligible dividends are grossed up by 15% and non-eligible by 38%.
Eligible and non-eligible gross-up rates are swapped · case 02
Eligible dividends are grossed up by 15% and non-eligible by 38%.
Eligible and non-eligible gross-up rates are swapped · case 03
Eligible dividends are grossed up by 15% and non-eligible by 38%.
Eligible and non-eligible gross-up rates are swapped · case 04
Eligible dividends are grossed up by 15% and non-eligible by 38%.
Eligible and non-eligible gross-up rates are swapped · case 05
Eligible dividends are grossed up by 15% and non-eligible by 38%.
Excess dividend credit is paid out as a refund · case 01
A retiree living on eligible dividends gets a negative tax.
Excess dividend credit is paid out as a refund · case 02
A retiree living on eligible dividends gets a negative tax.
Excess dividend credit is paid out as a refund · case 03
A retiree living on eligible dividends gets a negative tax.
Excess dividend credit is paid out as a refund · case 04
A retiree living on eligible dividends gets a negative tax.
Excess dividend credit is paid out as a refund · case 05
A retiree living on eligible dividends gets a negative tax.
Cash dividends rather than grossed-up dividends are included in taxable income · case 01
Taxable income is understated while the credit is still based on the gross-up.
Cash dividends rather than grossed-up dividends are included in taxable income · case 02
Taxable income is understated while the credit is still based on the gross-up.
Cash dividends rather than grossed-up dividends are included in taxable income · case 03
Taxable income is understated while the credit is still based on the gross-up.
Cash dividends rather than grossed-up dividends are included in taxable income · case 04
Taxable income is understated while the credit is still based on the gross-up.
Cash dividends rather than grossed-up dividends are included in taxable income · case 05
Taxable income is understated while the credit is still based on the gross-up.
Unearned income above the first deduction tier is taxed at the parent's rate · case 01
Unearned income between 1300 and 2600 is taxed at the parent's rate instead of the child's.
Unearned income above the first deduction tier is taxed at the parent's rate · case 02
Unearned income between 1300 and 2600 is taxed at the parent's rate instead of the child's.
Unearned income above the first deduction tier is taxed at the parent's rate · case 03
Unearned income between 1300 and 2600 is taxed at the parent's rate instead of the child's.
Unearned income above the first deduction tier is taxed at the parent's rate · case 04
Unearned income between 1300 and 2600 is taxed at the parent's rate instead of the child's.
Unearned income above the first deduction tier is taxed at the parent's rate · case 05
Unearned income between 1300 and 2600 is taxed at the parent's rate instead of the child's.
Earned income is counted toward the parent-rate amount · case 01
A working teenager's wages are taxed at the parent's rate.
Earned income is counted toward the parent-rate amount · case 02
A working teenager's wages are taxed at the parent's rate.
Earned income is counted toward the parent-rate amount · case 03
A working teenager's wages are taxed at the parent's rate.
Earned income is counted toward the parent-rate amount · case 04
A working teenager's wages are taxed at the parent's rate.
Earned income is counted toward the parent-rate amount · case 05
A working teenager's wages are taxed at the parent's rate.
The child receives the full standard deduction · case 01
Unearned income of a child is sheltered by the full 14600 deduction.
The child receives the full standard deduction · case 02
Unearned income of a child is sheltered by the full 14600 deduction.
The child receives the full standard deduction · case 03
Unearned income of a child is sheltered by the full 14600 deduction.
The child receives the full standard deduction · case 04
Unearned income of a child is sheltered by the full 14600 deduction.
The child receives the full standard deduction · case 05
Unearned income of a child is sheltered by the full 14600 deduction.
All taxable income is taxed at the parent's rate once there is any net unearned income · case 01
A child with 2601 of unearned income and wages pays the parent's rate on everything.
All taxable income is taxed at the parent's rate once there is any net unearned income · case 02
A child with 2601 of unearned income and wages pays the parent's rate on everything.
All taxable income is taxed at the parent's rate once there is any net unearned income · case 03
A child with 2601 of unearned income and wages pays the parent's rate on everything.
All taxable income is taxed at the parent's rate once there is any net unearned income · case 04
A child with 2601 of unearned income and wages pays the parent's rate on everything.
All taxable income is taxed at the parent's rate once there is any net unearned income · case 05
A child with 2601 of unearned income and wages pays the parent's rate on everything.
Provisional income counts the full benefit instead of half · case 01
Retirees cross the inclusion thresholds with far less other income.
Provisional income counts the full benefit instead of half · case 02
Retirees cross the inclusion thresholds with far less other income.
Provisional income counts the full benefit instead of half · case 03
Retirees cross the inclusion thresholds with far less other income.
Provisional income counts the full benefit instead of half · case 04
Retirees cross the inclusion thresholds with far less other income.
Provisional income counts the full benefit instead of half · case 05
Retirees cross the inclusion thresholds with far less other income.
The second-tier formula omits the amount included in the first tier · case 01
Income above the second base amount includes less benefit than stipulated.
The second-tier formula omits the amount included in the first tier · case 02
Income above the second base amount includes less benefit than stipulated.
The second-tier formula omits the amount included in the first tier · case 03
Income above the second base amount includes less benefit than stipulated.
The second-tier formula omits the amount included in the first tier · case 04
Income above the second base amount includes less benefit than stipulated.
The second-tier formula omits the amount included in the first tier · case 05
Income above the second base amount includes less benefit than stipulated.
Included benefits are not capped at 85% of benefits · case 01
High-income retirees include more than 85% of their benefits.
Included benefits are not capped at 85% of benefits · case 02
High-income retirees include more than 85% of their benefits.
Included benefits are not capped at 85% of benefits · case 03
High-income retirees include more than 85% of their benefits.
Included benefits are not capped at 85% of benefits · case 04
High-income retirees include more than 85% of their benefits.
Included benefits are not capped at 85% of benefits · case 05
High-income retirees include more than 85% of their benefits.
First-tier inclusion is not limited to half the benefits · case 01
Small benefits are included beyond half their amount between the base amounts.
First-tier inclusion is not limited to half the benefits · case 02
Small benefits are included beyond half their amount between the base amounts.
First-tier inclusion is not limited to half the benefits · case 03
Small benefits are included beyond half their amount between the base amounts.
First-tier inclusion is not limited to half the benefits · case 04
Small benefits are included beyond half their amount between the base amounts.
First-tier inclusion is not limited to half the benefits · case 05
Small benefits are included beyond half their amount between the base amounts.
Married-separate filers living together receive the single base amounts · case 01
Separate filers include nothing below 25000 of provisional income.
Married-separate filers living together receive the single base amounts · case 02
Separate filers include nothing below 25000 of provisional income.
Married-separate filers living together receive the single base amounts · case 03
Separate filers include nothing below 25000 of provisional income.
Married-separate filers living together receive the single base amounts · case 04
Separate filers include nothing below 25000 of provisional income.
Married-separate filers living together receive the single base amounts · case 05
Separate filers include nothing below 25000 of provisional income.
The phase-out is measured on earned income only · case 01
A filer with large investment-free non-wage income keeps the full credit.
The phase-out is measured on earned income only · case 02
A filer with large investment-free non-wage income keeps the full credit.
The phase-out is measured on earned income only · case 03
A filer with large investment-free non-wage income keeps the full credit.
The phase-out is measured on earned income only · case 04
A filer with large investment-free non-wage income keeps the full credit.
The phase-out is measured on earned income only · case 05
A filer with large investment-free non-wage income keeps the full credit.
Joint filers do not receive the higher phase-out start · case 01
Married couples lose credit earlier than stipulated.
Joint filers do not receive the higher phase-out start · case 02
Married couples lose credit earlier than stipulated.
Joint filers do not receive the higher phase-out start · case 03
Married couples lose credit earlier than stipulated.
Joint filers do not receive the higher phase-out start · case 04
Married couples lose credit earlier than stipulated.
Joint filers do not receive the higher phase-out start · case 05
Married couples lose credit earlier than stipulated.
Excess investment income only trims the credit · case 01
Filers with investment income over the limit still receive most of the credit.
Excess investment income only trims the credit · case 02
Filers with investment income over the limit still receive most of the credit.
Excess investment income only trims the credit · case 03
Filers with investment income over the limit still receive most of the credit.
Excess investment income only trims the credit · case 04
Filers with investment income over the limit still receive most of the credit.
Excess investment income only trims the credit · case 05
Filers with investment income over the limit still receive most of the credit.
Three or more children receive the two-child parameters · case 01
Larger families get the two-child maximum credit.
Three or more children receive the two-child parameters · case 02
Larger families get the two-child maximum credit.
Three or more children receive the two-child parameters · case 03
Larger families get the two-child maximum credit.
Three or more children receive the two-child parameters · case 04
Larger families get the two-child maximum credit.
Three or more children receive the two-child parameters · case 05
Larger families get the two-child maximum credit.
The phased-out credit becomes negative · case 01
High earners claiming the credit see an additional tax.
The phased-out credit becomes negative · case 02
High earners claiming the credit see an additional tax.
The phased-out credit becomes negative · case 03
High earners claiming the credit see an additional tax.
The phased-out credit becomes negative · case 04
High earners claiming the credit see an additional tax.
The phased-out credit becomes negative · case 05
High earners claiming the credit see an additional tax.
The gliding cap is applied to the whole income tax · case 01
Filers just above the limit pay the full 5.5% surcharge.
The gliding cap is applied to the whole income tax · case 02
Filers just above the limit pay the full 5.5% surcharge.
The gliding cap is applied to the whole income tax · case 03
Filers just above the limit pay the full 5.5% surcharge.
The gliding cap is applied to the whole income tax · case 04
Filers just above the limit pay the full 5.5% surcharge.
The gliding cap is applied to the whole income tax · case 05
Filers just above the limit pay the full 5.5% surcharge.
INSPECTABLE BY DESIGN
Every result has a runnable source.
Runnable implementations with recorded outputs, source hashes, and explicit contracts. Related variants share a failure mechanism and belong together in evaluation splits.
Read the methodology ↗