Methodology · AU-HOME-006
Offset Account Calculator
Model an offset balance and regular deposits against your mortgage: interest saved, time saved and the cash that stays available, kept distinct from principal.
Engines and formulas
- E07 · Scheduled mortgage ledger
A payment-period ledger with dated events (rates, extras, offsets, fees), §13.9 offset treatment and §12.5.8 reconciliation invariants on every period. Daily accrual is not modelled at P0.
Registered formulas: §13.7 recurrence · §13.9 offset
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.