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Extra Repayments Calculator

AustraliaScheduled modelClass B · rule-based estimateNo statutory rules requiredMethodology
AUD
Enter the annual rate as a percentage, like 5.99.

Repay interest only for the first years, then principal and interest.

AUD
AUD
Defaults to the first repayment, 1 Oct 2026.

Enter your loan and an extra repayment to see the interest and time saved.

Summary

Two ledgers run on identical dates: one with your extra repayments, one without. The difference between their interest totals and their period counts is what is reported as saved.

Working

  1. §13.5 payment — the scheduled repayment solves P = B·i ÷ (1 − (1 + i)^−n) from the balance B, the periodic rate i and the remaining periods n.
  2. §13.7 recurrence — each period: interest = accruing balance × i, then closing = opening + interest + fees − payment − extra repayment.
  3. §13.9 offset — interest accrues on max(0, balance − offset × effectiveness), floored at zero; offset cash is never a principal repayment.
  4. §12.5.8 reconciliation — the ledger identity is checked on every period. A reconciliation failure invalidates the result rather than warning about it.

Assumptions

  • Interest accrues once per repayment period on the payment-period ledger. Daily accrual is not modelled at P0.
  • The first repayment falls on 1 October 2026; every date in the schedule follows from that and the repayment frequency.
  • The rate is held constant except where a dated rate-change event moves it.
  • Weekly, fortnightly and monthly frequencies use 52, 26 and 12 periods per year.

Limitations

  • Lender daily accrual, transaction timing, fee timing and rounding can differ from this model; compare the settings with your loan contract and statements.
  • Redraw availability, offset eligibility conditions, break costs and any lender fee that was not entered are not modelled.
  • Amounts beyond the entered term are not projected; a balance left unpaid at term is reported rather than extended.