Why Overpay Your Mortgage?
A mortgage is typically the largest debt most people carry, and the interest costs over a full 25–30 year term can exceed the original purchase price of the property. Overpaying — even by a modest amount — reduces the outstanding principal on which interest is charged, creating a compounding saving effect over time.
UK Mortgages: The 10% Annual Overpayment Allowance
Most UK fixed-rate mortgage deals permit overpayments of up to 10% of the outstanding balance per year without early repayment charges (ERCs). For example, on a £200,000 mortgage, you can typically overpay up to £20,000 per year without penalty. Overpaying beyond the allowance during a fixed-rate period can trigger significant charges — always check your mortgage terms or contact your lender before making large overpayments.
On tracker and standard variable rate (SVR) mortgages, there is usually no limit on overpayments and no ERCs.
Australian Mortgages: Offset Accounts and Redraw
Australian lenders commonly offer two mechanisms to reduce interest beyond regular repayments:
- Offset account: A transactional account linked to your mortgage. The balance in the offset account reduces the principal on which interest is calculated. £10,000 sitting in an offset against a £300,000 mortgage means you pay interest only on £290,000.
- Redraw facility: Extra repayments go directly into the loan, reducing the balance and interest. You can redraw the extra payments if needed (subject to lender terms), making it a flexible emergency fund.
One-Off vs Regular Overpayments
Both strategies help — but consistent small regular overpayments often outperform sporadic lump sums because they start reducing interest accrual immediately. Use the Ohkayy Mortgage Calculator linked above to compare monthly overpayment scenarios. If you receive a bonus, tax refund, or inheritance, check your lender's overpayment allowance before applying it as a lump sum.