The average mortgage rate breached 5.50% for the first time since August 2024, according to Moneyfacts data recorded on 25 March 2026. This is an unwelcome milestone. Early March saw average rates at 4.89% - meaning borrowers have absorbed a 0.61 percentage point rise in just weeks. The cause: rising swap rates (the benchmark lenders use to price fixed-rate mortgages), pushed up by Middle East geopolitical tensions and oil price increases affecting lender funding costs.
What the Rate Rise Costs You Each Month
Run the numbers. On a £200,000 interest-only BTL (buy-to-let) mortgage at 5.50%, your monthly payment is £917. At the 4.89% rate from early March, that same mortgage cost £815 per month. That is £102 more every month, or £1,224 more per year - and that is on a single property.
Lender movement has been sharp (What Mortgage, 26 March 2026). Virgin Money raised rates by 0.70%. Santander increased by up to 0.53%. But the squeeze goes beyond rates. Both HSBC and Santander cut maximum loan sizes to comply with regulatory stress tests. Borrowers who were previously offered 5.5 to 6 times their salary income multiple are now capped at 4.5 times. That directly affects how much you can borrow for your next purchase.
Where Rates Head from Here
Aaron Strutt at Trinity Financial noted that high salary multiples "are probably okay when rates are below 4%" - which means the current rate environment sits outside comfortable borrowing territory for many investors. Adam French at Moneyfacts forecasts stabilisation at 5.75% to 6.00% if further base rate rises come through, given that mortgage rates have historically run 1.5 to 1.75 percentage points above base rate.
Dariusz Karpowicz at Albion Financial Advice captured the mood bluntly: "When nobody wants to be the cheapest on the best buy tables, you know the mood has shifted." Lenders are defensive. If you are mid-application or your rate lock expires soon, you may wish to speak to your broker about securing terms before further volatility.
