What Does a 1% Mortgage Rate Rise Do to Your Payment?

Why the payment moves by more than the headline suggests

An amortising mortgage payment covers both interest and principal. When the rate changes, the lender recalculates the payment needed to repay the outstanding balance over the remaining term. A rate moving from 4% to 5% is a one-percentage-point increase, but it is a 25% increase in the interest rate itself.

A worked repayment example

For an illustrative repayment mortgage with a 250,000 balance and 25 years remaining, the standard monthly principal-and-interest payment is approximately 1,319.59 at 4%. At 5%, it becomes approximately 1,461.48. The estimated increase is 141.89 a month, or about 1,703 a year.

This excludes taxes, insurance, service charges and product fees. Actual lender figures may use daily interest, different rounding and a payment date that changes the first recalculated amount.

Balance and term both matter

A larger balance exposes more money to the higher rate. A longer remaining term usually produces a smaller immediate payment than repaying the same balance quickly, but it can leave the higher rate applying for more years. Two households with the same rate can therefore see very different changes.

Fixed, tracker and variable mortgages behave differently

A fixed-rate payment usually remains unchanged during the fixed period, subject to the product terms. A tracker follows a reference rate plus a margin. A lender's standard variable rate can change at the lender's discretion. The point at which a new rate affects you depends on the product, reset date and any refinancing or remortgaging decision.

What to check before the new payment begins

• Outstanding balance and exact remaining term.
• Whether the quoted rate includes a product fee.
• Early-repayment charges on the current mortgage.
• Whether overpayments are allowed without a charge.
• The cost and break-even period of switching.
• Whether the household budget can absorb a higher-rate scenario.

Run several rates rather than only the one currently offered. A stress test at one and two percentage points above the expected rate can reveal whether the payment remains manageable. For decisions with material consequences, confirm the payment and fees directly with the lender or a qualified mortgage professional.

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