Methodology · AU-DEBT-012
How the Credit Card Payoff Calculator works
This page documents how the Credit Card Payoff Calculator produces its figures: the engines and formulas it runs, the rule packs it reads statutory values from, the official documents those packs cite, and how the engines are verified.
Engines and formulas
- E12 · Revolving credit engine
Monthly statement cycles: interest on the opening balance, configurable minimum rule (percent with floor), fixed-payment strategy, promotional expiry on its exact date.
Registered formulas: §12.11 cycles
Verification
Engines carry boundary tests at every bracket edge, property-based tests, reconciliation invariants and, where official worked examples exist, tests that reproduce them exactly. The full source register is on the sources page.