Property · Rental deductions

Rental Interest Apportionment Calculator

Separate deductible rental interest from private redraws, unavailable days and another owner’s share.

Mixed-purpose loanPrivate redrawsCo-ownership
01LOAN AND RENTAL USE

Redraws for a home, car or other private use remain private debt.

02INTEREST SPLIT
Awaiting input

Enter the loan balance and interest charged.

What this estimate includes

  • Interest follows the use of the borrowed money, not the property used as security.
  • Private redraws must remain separately identifiable in a mixed loan.
  • The property must be rented or genuinely available for rent during the claimed period.

Frequently asked questions

Can I claim all interest on an investment loan?
Only to the extent the borrowed money is used to produce rental income and the property is rented or genuinely available for rent.
What happens if I redraw for a private purchase?
The private redraw creates a non-deductible portion of the mixed loan. Paying down the loan later does not automatically turn that private portion back into rental debt.
How do joint owners split rental interest?
Co-owners generally claim rental income and expenses according to their legal ownership interests. This calculator applies the ownership percentage you enter.

Tax Accuracy & Sources

Reviewed: 30 July 2026 · Tax year: General rental-interest rules

Straight-line apportionment estimate only. Mixed loans with fluctuating balances require transaction-level records; refinancing, construction periods and non-commercial arrangements need separate review.