Does an Offset Lower Repayments or Shorten Your Loan?

Short answer

Money in an offset account does not lower your minimum repayment; that figure stays fixed. What it lowers is the interest you're charged each period, so more of every (unchanged) repayment goes to principal. The result is that your loan is paid off earlier, with less total interest. The honest answer, then: an offset shortens your loan term, it doesn't reduce your repayments.

How an offset account actually works

An offset account is an everyday transaction account linked to your home loan. Each day, your lender subtracts the offset balance from your loan balance before working out interest. If you owe $600,000 and hold $30,000 in offset, interest is calculated as if you owed $570,000, but you still owe the full $600,000 and your contractual repayment is unchanged.

Moneysmart puts it plainly: "the loan balance stays the same so the minimum repayments do too. However, you're charged less interest, so the loan balance goes down quicker as more of your repayment goes to the principal."

That's the whole mechanism. Your repayment is set when the loan starts, based on the full balance, rate and term. An offset doesn't change that number; it changes the split of each repayment. Less interest means a bigger principal slice, so the balance falls faster than the schedule expects and the loan clears before the official end date. Because you don't earn interest on offset money, the "return" is the home-loan interest you avoid: effectively a tax-free saving at your loan rate.

This is different from a lender recalculating your repayment downward, which some loans do after lump sums. A standard offset leaves the repayment alone and converts the saving into a shorter term. See offset account vs redraw for how that compares to a redraw facility.

Worked example: $30,000 offset on a $600k loan

Take a $600,000 loan at 6.00% p.a. over 30 years, paid monthly.

	No offset	$30,000 offset (constant)
Monthly repayment	$3,597	$3,597 (same)
Interest charged, month 1	$600,000 × 0.5% = $3,000	$570,000 × 0.5% = $2,850
Principal paid, month 1	$597	$747
Time to repay	30 years	~27 years
Total interest	~$695,000	~$563,000

The maths is checkable. The monthly rate is 6% ÷ 12 = 0.5%. In month one, the offset cuts interest by $30,000 × 0.5% = $150. Because the $3,597 repayment is fixed, that $150 is redirected to principal. Repeat every month and the loan finishes roughly 3 years early, saving about $131,000 in interest over the life of the loan, all while you keep the $30,000 fully accessible.

Notice the repayment number never moved. Every dollar of benefit shows up as a shorter term and lower total interest, never as a smaller monthly bill. (For a deeper version of these numbers, see how much an offset saves on a $600k loan.)

Model this in True Loan

You can test your own figures at trueloan.app. It's free and runs entirely in your browser.

1. Set Loan amount, Interest rate, Term and Repayment frequency to your loan.
2. Enter your balance in the dedicated Offset balance input.
3. Read the remaining-debt timeline and total interest, and watch the repayment figure stay constant while the payoff date moves earlier.

One thing to keep straight: the Offset balance and Extra repayment ($/month) are two separate inputs that work differently. An offset keeps your repayment the same and shortens the term; an extra repayment actually increases what leaves your account each month. To see them side by side, use the comparison tool at trueloan.app/compare and put your offset in scenario A and an equivalent extra repayment in scenario B. More on that in offset vs extra repayments.

Common questions and mistakes

"Will my bank lower my monthly payment if I keep money in offset?" No. A standard offset never reduces the contractual repayment. It only reduces interest and shortens the term.

"Does the offset have to stay full?" True Loan models a constant offset balance. In reality the saving rises and falls with your day-to-day balance; spending the money reduces the benefit, since interest is recalculated daily.

"Is this the same as paying extra?" The interest effect is similar dollar-for-dollar, but an offset keeps the money accessible while extra repayments lock it into the loan (recoverable only via redraw, if offered).

"Do I save tax?" You don't earn (taxable) interest on offset cash; you avoid loan interest instead. Moneysmart's guide to paying off your mortgage faster explains why that's often more valuable than savings interest after tax.

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Figures here are estimates for the 2025–26 financial year and depend on your rate, balance and lender's rules. This is general information, not financial or credit advice. Check your loan contract and official sources such as moneysmart.gov.au.