How UK Mortgage Rates Work

UK mortgage rates are not set by lenders in isolation — they are derived from the Bank of England base rate, lender funding costs in the swap market, competitive positioning, and the cost of capital each bank has to hold against the loan. This guide unpacks each piece in plain English.

The four product types

UK lenders offer four broad product types: fixed-rate mortgages (typically two, five, or ten years), tracker mortgages (priced at base rate plus a margin and floating with every MPC move), discounted variable-rate mortgages (priced at a discount to the lender’s SVR for a fixed period), and the standard variable rate (SVR) itself, which is what you fall onto when any of the above expires.

Each product type passes the base rate through to the borrower differently. A tracker passes the rate through within days of an MPC decision — usually one billing cycle. The SVR is a managed rate the lender adjusts at its discretion, typically following base-rate moves with a one-to-three month lag. Fixed-rate deals do not move at all during the fix period — they are priced once at offer and held until the fix expires. New fixed-rate deals priced for new customers move with the swap-rate curve, not directly with the base rate.

Why the swap curve matters more than the base rate for fixes

When a lender writes a five-year fixed-rate mortgage, it does not simply lend out customer deposits at the base rate — that would leave the lender exposed if interest rates rose during the fix. Instead, the lender enters into a five-year interest rate swap with another bank, paying a fixed rate for five years in exchange for receiving the floating overnight rate. The fixed leg of that swap is the lender’s funding cost; everything on top is margin, capital cost, and credit risk premium.

This is why fixed-rate mortgages can become cheaper or more expensive even when the base rate is unchanged. If market expectations of future base-rate moves shift, the swap curve shifts immediately, and new fixed-rate mortgage offers follow within days. Existing fixed-rate borrowers see no change until their fix expires.

The Sterling Overnight Index Average (SONIA) curve is the canonical reference. As of mid-2026 the two-year, five-year, and ten-year SONIA points were trading in a relatively flat configuration around the prevailing base rate, which compressed the spread between two-year and five-year fixed mortgage products to roughly fifteen basis points.

Loan-to-value bands and risk pricing

Every UK lender prices its mortgage range by loan-to-value band: typically 60%, 75%, 80%, 85%, 90%, and 95%. A 60% LTV deal is the cheapest because the lender’s loss-given-default in any reasonable house-price scenario is essentially zero. A 95% LTV deal is meaningfully more expensive — typically 60 to 120 basis points above the 60% LTV equivalent — because a modest house-price fall could leave the loan unsecured.

For the lender, the LTV band feeds into both the headline rate and the regulatory capital required to be held against the loan. Higher LTV loans require materially more capital under the UK’s standardised credit-risk approach, and that capital cost is passed through to the borrower in the headline rate.

The LTV that matters is the one at the time of application, not the LTV that develops naturally over the life of the loan as the borrower repays principal and the house appreciates. A borrower with an 85% LTV at first application can remortgage at 75% LTV two years later if they have repaid principal and the house has appreciated even slightly — typically saving thirty to sixty basis points on the next deal.

How the base rate transmits through the system

When the Monetary Policy Committee changes the Bank Rate, the transmission to retail mortgage rates plays out in distinct timeframes. Tracker mortgages reprice within one billing cycle — usually a single calendar month. Standard variable rates are repriced by the lender, typically with one to three months of lag, and not always one-for-one with the base-rate move; lenders can absorb part of a cut into their margin or pass through more than the move in a tightening cycle.

New fixed-rate deals reprice within weeks because the swap curve moves immediately on MPC decisions and on the surrounding minutes and market expectations. Existing fixed-rate borrowers experience zero change during their fix period — that is the whole point of the product — and meet the new rate environment only at the maturity of their current deal.

A 25-basis-point base-rate change translates into roughly £14 per month on each £100,000 of outstanding mortgage on a 25-year repayment basis. A household with a £200,000 mortgage on a tracker product sees its monthly payment rise by approximately £28 within one month of a quarter-point hike, and falls by the same amount on a cut.

Reading a best-buy table critically

Best-buy tables show the lowest headline rate in each LTV band and fix length, but the lowest headline rate is not always the cheapest deal once arrangement fees are accounted for. A 4.49% rate with a £999 arrangement fee can be more expensive over a two-year fix than a 4.69% rate with no fee, depending on the loan size; the breakeven loan amount is typically around £125,000 to £150,000.

Treat the headline rate as a starting point and run the cost over the full fix period including any product fee, valuation fee, and broker fee. The annual percentage rate of charge (APRC) shown on official illustrations folds these in but extrapolates to the rest of the term on the lender’s SVR, so it can overstate the cost difference for someone who plans to remortgage at fix expiry.

Frequently asked questions

UK mortgage rate snapshot — selected LTV bands

"The Bank of England Bank Rate sets the floor for UK mortgage pricing — but lender margins, LTV-band step-ups, and Affordability Test arithmetic determine the actual rate you pay."