An offset mortgage links a savings account to your mortgage. Whatever sits in that account is deducted from the balance you pay interest on — hold savings worth a tenth of your mortgage and you pay interest on nine tenths of it. You earn no interest on the savings, but you also pay no tax on the benefit — which for a higher-rate taxpayer often beats what the same money would earn in a savings account. The money stays yours and stays accessible.
Who offsets genuinely suit
- Higher and additional-rate taxpayers, where the tax-free benefit is largest
- Self-employed people holding money back for a tax bill
- Anyone with a substantial emergency fund they want to keep liquid
- People who receive irregular lump sums — bonuses, dividends, commission
The two ways to take the benefit
You can either reduce your monthly payment while keeping the term the same, or keep the payment the same and shorten the term. The second is where offsets do their most impressive work: leaving the payment untouched means the extra effectively overpays the mortgage, and on a decent balance that can take years off the term.
The trade-off
Offset products often carry a slightly higher headline rate than the sharpest mainstream deals. Whether that is worth paying depends on how much you keep in savings relative to the mortgage. As a rough guide, the more you hold and the higher your tax rate, the more likely an offset wins. Below a modest savings balance it usually doesn't.
Family offsets
Some lenders allow a family member's savings to offset against a borrower's mortgage — often used to help a first-time buyer borrow more or put down less, without the family member gifting the money away. The savings remain theirs and are usually released after a set period.