💡 Mortgage Offset Account Calculator

Every dollar in your offset cuts the interest on your loan. See how much.

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Formula at a glance

Offset Account Calculator: Monthly interest — (loan − offset) × rate ÷ 12. Example: $600,000 loan, $50,000 offset + $500 a month → Interest saved: $331,329
How the Offset Account Calculator works: Monthly interest — (loan − offset) × rate ÷ 12

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📘 About the Mortgage Offset Account Calculator

An offset account is a transaction account linked to your home loan. Its balance is subtracted from the loan before interest is calculated, but the money stays yours to use.

Keeping repayments the same, the interest saved goes straight to paying off the loan, so you finish years early. Saving at your mortgage rate is like earning that rate tax-free.

🧮 Formula

Monthly interest
(loan − offset) × rate ÷ 12

✏️ Worked examples

$600,000 loan, $50,000 offset + $500 a month

You enter
Loan balance600,000 $
Interest rate6%
Years remaining30 years
Offset balance50,000 $
Added to offset each month500 $
You get
Interest saved$331,329
Loan paid off22.3 years (7.7 years sooner)
Monthly repayment (unchanged)$3,597.30
Interest without offset$695,029
Interest with offset$363,700
First-month saving$250.00

$331,329.

$400,000 loan, $20,000 offset

You enter
Loan balance400,000 $
Interest rate6%
Years remaining30 years
Offset balance20,000 $
Added to offset each month0 $
You get
Interest saved$87,730
Loan paid off27 years (3 years sooner)
Monthly repayment (unchanged)$2,398.20
Interest without offset$463,353
Interest with offset$375,623
First-month saving$100.00

$87,730.

🧭 How to use this calculator

What you enter

  • Loan balance ($)
  • Interest rate (%)
  • Years remaining (years)
  • Offset balance ($)
  • Added to offset each month ($)

What you get

  • Interest saved
  • Loan paid off
  • Monthly repayment (unchanged)
  • Interest without offset
  • Interest with offset
  • First-month saving

❓ Frequently asked questions

Is an offset account worth it?

Usually yes if you keep a decent balance (often $10,000+), since it saves interest at your loan rate without tax.

Offset or redraw?

Both save the same interest. Offset money is clearly yours and easier to access; redraw can be restricted and matters for tax on investment loans.

Does an offset account reduce repayments?

Normally no — repayments stay the same and the loan is paid off faster.

Is offset interest taxed?

No, you are not earning interest, you are saving it.