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
Net-pay deduction priority and arrears: all-or-nothing deduction · case 01
Deductions that must be taken in full are partially taken when pay is short.
Net-pay deduction priority and arrears: all-or-nothing deduction · case 02
Deductions that must be taken in full are partially taken when pay is short.
Net-pay deduction priority and arrears: all-or-nothing deduction · case 03
Deductions that must be taken in full are partially taken when pay is short.
Net-pay deduction priority and arrears: all-or-nothing deduction · case 04
Deductions that must be taken in full are partially taken when pay is short.
Net-pay deduction priority and arrears: all-or-nothing deduction · case 05
Deductions that must be taken in full are partially taken when pay is short.
Net-pay deduction priority and arrears: arrears recording test · case 01
Fully paid deductions appear in the arrears report with zero balances.
Net-pay deduction priority and arrears: arrears recording test · case 02
Fully paid deductions appear in the arrears report with zero balances.
Net-pay deduction priority and arrears: arrears recording test · case 03
Fully paid deductions appear in the arrears report with zero balances.
Net-pay deduction priority and arrears: arrears recording test · case 04
Fully paid deductions appear in the arrears report with zero balances.
Net-pay deduction priority and arrears: arrears recording test · case 05
Fully paid deductions appear in the arrears report with zero balances.
Group-term life imputed income: age band boundary · case 01
Employees exactly at a band's starting age are charged the younger band's rate.
Group-term life imputed income: age band boundary · case 02
Employees exactly at a band's starting age are charged the younger band's rate.
Group-term life imputed income: age band boundary · case 03
Employees exactly at a band's starting age are charged the younger band's rate.
Group-term life imputed income: age band boundary · case 04
Employees exactly at a band's starting age are charged the younger band's rate.
Group-term life imputed income: age band boundary · case 05
Employees exactly at a band's starting age are charged the younger band's rate.
Group-term life imputed income: coverage exclusion · case 01
Employees with modest coverage have imputed income on the first 50,000 of coverage.
Group-term life imputed income: coverage exclusion · case 02
Employees with modest coverage have imputed income on the first 50,000 of coverage.
Group-term life imputed income: coverage exclusion · case 03
Employees with modest coverage have imputed income on the first 50,000 of coverage.
Group-term life imputed income: coverage exclusion · case 04
Employees with modest coverage have imputed income on the first 50,000 of coverage.
Group-term life imputed income: coverage exclusion · case 05
Employees with modest coverage have imputed income on the first 50,000 of coverage.
Group-term life imputed income: employee payment offset · case 01
Employees paying part of the premium after tax still see the full imputed cost.
Group-term life imputed income: employee payment offset · case 02
Employees paying part of the premium after tax still see the full imputed cost.
Group-term life imputed income: employee payment offset · case 03
Employees paying part of the premium after tax still see the full imputed cost.
Group-term life imputed income: employee payment offset · case 04
Employees paying part of the premium after tax still see the full imputed cost.
Group-term life imputed income: employee payment offset · case 05
Employees paying part of the premium after tax still see the full imputed cost.
W-4 exempt claim expiration: expiry year · case 01
Exempt forms filed after mid-February expire immediately.
W-4 exempt claim expiration: expiry year · case 02
Exempt forms filed after mid-February expire immediately.
W-4 exempt claim expiration: expiry year · case 03
Exempt forms filed after mid-February expire immediately.
W-4 exempt claim expiration: expiry year · case 04
Exempt forms filed after mid-February expire immediately.
W-4 exempt claim expiration: expiry year · case 05
Exempt forms filed after mid-February expire immediately.
W-4 exempt claim expiration: expiry day inclusion · case 01
Paychecks dated exactly February 15 lose exempt status one day early.
W-4 exempt claim expiration: expiry day inclusion · case 02
Paychecks dated exactly February 15 lose exempt status one day early.
W-4 exempt claim expiration: expiry day inclusion · case 03
Paychecks dated exactly February 15 lose exempt status one day early.
W-4 exempt claim expiration: expiry day inclusion · case 04
Paychecks dated exactly February 15 lose exempt status one day early.
W-4 exempt claim expiration: expiry day inclusion · case 05
Paychecks dated exactly February 15 lose exempt status one day early.
W-4 exempt claim expiration: claim chronology · case 01
A newer W-4 entered before an older one in the list is overridden by the older form.
W-4 exempt claim expiration: claim chronology · case 02
A newer W-4 entered before an older one in the list is overridden by the older form.
W-4 exempt claim expiration: claim chronology · case 03
A newer W-4 entered before an older one in the list is overridden by the older form.
W-4 exempt claim expiration: claim chronology · case 04
A newer W-4 entered before an older one in the list is overridden by the older form.
W-4 exempt claim expiration: claim chronology · case 05
A newer W-4 entered before an older one in the list is overridden by the older form.
W-4 exempt claim expiration: claim effective date · case 01
A W-4 received on the pay date is ignored for that paycheck.
W-4 exempt claim expiration: claim effective date · case 02
A W-4 received on the pay date is ignored for that paycheck.
W-4 exempt claim expiration: claim effective date · case 03
A W-4 received on the pay date is ignored for that paycheck.
W-4 exempt claim expiration: claim effective date · case 04
A W-4 received on the pay date is ignored for that paycheck.
W-4 exempt claim expiration: claim effective date · case 05
A W-4 received on the pay date is ignored for that paycheck.
W-4 exempt claim expiration: non-exempt claim handling · case 01
Employees who file a regular W-4 are withheld at the default rate, ignoring their form.
W-4 exempt claim expiration: non-exempt claim handling · case 02
Employees who file a regular W-4 are withheld at the default rate, ignoring their form.
W-4 exempt claim expiration: non-exempt claim handling · case 03
Employees who file a regular W-4 are withheld at the default rate, ignoring their form.
W-4 exempt claim expiration: non-exempt claim handling · case 04
Employees who file a regular W-4 are withheld at the default rate, ignoring their form.
W-4 exempt claim expiration: non-exempt claim handling · case 05
Employees who file a regular W-4 are withheld at the default rate, ignoring their form.
Aggregate-method supplemental withholding: credit for actual withholding · case 01
Employees with W-4 extra withholding on regular pay are under-withheld on bonuses paid with that run.
Aggregate-method supplemental withholding: credit for actual withholding · case 02
Employees with W-4 extra withholding on regular pay are under-withheld on bonuses paid with that run.
Aggregate-method supplemental withholding: credit for actual withholding · case 03
Employees with W-4 extra withholding on regular pay are under-withheld on bonuses paid with that run.
Aggregate-method supplemental withholding: credit for actual withholding · case 04
Employees with W-4 extra withholding on regular pay are under-withheld on bonuses paid with that run.
Aggregate-method supplemental withholding: credit for actual withholding · case 05
Employees with W-4 extra withholding on regular pay are under-withheld on bonuses paid with that run.
Aggregate-method supplemental withholding: standalone supplemental credit · case 01
Bonuses paid in a separate run are withheld as if regular wages had no withholding.
Aggregate-method supplemental withholding: standalone supplemental credit · case 02
Bonuses paid in a separate run are withheld as if regular wages had no withholding.
Aggregate-method supplemental withholding: standalone supplemental credit · case 03
Bonuses paid in a separate run are withheld as if regular wages had no withholding.
Aggregate-method supplemental withholding: standalone supplemental credit · case 04
Bonuses paid in a separate run are withheld as if regular wages had no withholding.
Aggregate-method supplemental withholding: standalone supplemental credit · case 05
Bonuses paid in a separate run are withheld as if regular wages had no withholding.
Aggregate-method supplemental withholding: aggregate wage base · case 01
Bonuses for higher earners are withheld at the bottom bracket.
Aggregate-method supplemental withholding: aggregate wage base · case 02
Bonuses for higher earners are withheld at the bottom bracket.
Aggregate-method supplemental withholding: aggregate wage base · case 03
Bonuses for higher earners are withheld at the bottom bracket.
Aggregate-method supplemental withholding: aggregate wage base · case 04
Bonuses for higher earners are withheld at the bottom bracket.
Aggregate-method supplemental withholding: aggregate wage base · case 05
Bonuses for higher earners are withheld at the bottom bracket.
Applicable minimum wage and youth rate: most protective rate · case 01
Employees in cities with a minimum wage below the state rate are underpaid.
Applicable minimum wage and youth rate: most protective rate · case 02
Employees in cities with a minimum wage below the state rate are underpaid.
Applicable minimum wage and youth rate: most protective rate · case 03
Employees in cities with a minimum wage below the state rate are underpaid.
Applicable minimum wage and youth rate: most protective rate · case 04
Employees in cities with a minimum wage below the state rate are underpaid.
Applicable minimum wage and youth rate: most protective rate · case 05
Employees in cities with a minimum wage below the state rate are underpaid.
Applicable minimum wage and youth rate: youth window length · case 01
Young workers on their 90th day are shortchanged or overpaid at the window edge.
Applicable minimum wage and youth rate: youth window length · case 02
Young workers on their 90th day are shortchanged or overpaid at the window edge.
Applicable minimum wage and youth rate: youth window length · case 03
Young workers on their 90th day are shortchanged or overpaid at the window edge.
Applicable minimum wage and youth rate: youth window length · case 04
Young workers on their 90th day are shortchanged or overpaid at the window edge.
Applicable minimum wage and youth rate: youth window length · case 05
Young workers on their 90th day are shortchanged or overpaid at the window edge.
Applicable minimum wage and youth rate: youth rate preemption · case 01
Young workers in states with their own minimum wage are paid the youth rate.
Applicable minimum wage and youth rate: youth rate preemption · case 02
Young workers in states with their own minimum wage are paid the youth rate.
Applicable minimum wage and youth rate: youth rate preemption · case 03
Young workers in states with their own minimum wage are paid the youth rate.
Applicable minimum wage and youth rate: youth rate preemption · case 04
Young workers in states with their own minimum wage are paid the youth rate.
Applicable minimum wage and youth rate: youth rate preemption · case 05
Young workers in states with their own minimum wage are paid the youth rate.
Cumulative wages withholding method: annualization base · case 01
Employees on the cumulative method are withheld as if on the ordinary per-period method.
Cumulative wages withholding method: annualization base · case 02
Employees on the cumulative method are withheld as if on the ordinary per-period method.
Cumulative wages withholding method: annualization base · case 03
Employees on the cumulative method are withheld as if on the ordinary per-period method.
Cumulative wages withholding method: annualization base · case 04
Employees on the cumulative method are withheld as if on the ordinary per-period method.
Cumulative wages withholding method: annualization base · case 05
Employees on the cumulative method are withheld as if on the ordinary per-period method.
Cumulative wages withholding method: tax to date proration · case 01
Withholding collapses to a single period's share of tax despite prior withholding being subtracted.
Cumulative wages withholding method: tax to date proration · case 02
Withholding collapses to a single period's share of tax despite prior withholding being subtracted.
Cumulative wages withholding method: tax to date proration · case 03
Withholding collapses to a single period's share of tax despite prior withholding being subtracted.
Cumulative wages withholding method: tax to date proration · case 04
Withholding collapses to a single period's share of tax despite prior withholding being subtracted.
Cumulative wages withholding method: tax to date proration · case 05
Withholding collapses to a single period's share of tax despite prior withholding being subtracted.
Cumulative wages withholding method: bracket upper tier · case 01
High earners are withheld far more than the bracket schedule implies.
Cumulative wages withholding method: bracket upper tier · case 02
High earners are withheld far more than the bracket schedule implies.
Cumulative wages withholding method: bracket upper tier · case 03
High earners are withheld far more than the bracket schedule implies.
Cumulative wages withholding method: bracket upper tier · case 04
High earners are withheld far more than the bracket schedule implies.
Cumulative wages withholding method: bracket upper tier · case 05
High earners are withheld far more than the bracket schedule implies.
Multi-state wage allocation by work days: zero-day fallback · case 01
Remote employees with no recorded work days have wages allocated to no state.
Multi-state wage allocation by work days: zero-day fallback · case 02
Remote employees with no recorded work days have wages allocated to no state.
Multi-state wage allocation by work days: zero-day fallback · case 03
Remote employees with no recorded work days have wages allocated to no state.
Multi-state wage allocation by work days: zero-day fallback · case 04
Remote employees with no recorded work days have wages allocated to no state.
Multi-state wage allocation by work days: zero-day fallback · case 05
Remote employees with no recorded work days have wages allocated to no state.
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 ↗