Swap Rates: The figure that really matters in the fixed rate mortgage market

Swap rates are rarely mentioned in mainstream news yet they often matter more to your mortgage than the Bank of England’s headline rate. If swap rates fall, fixed mortgage rates usually follow. If swap rates rise, lenders increase fixed rates even if the Bank of England does nothing.

Swap rates are the single biggest influencer on the fixed rate mortgage market and can determine how affordable or expensive your mortgage is as well as the choice of mortgages available, irrespective of the Bank of England’s position. So, what exactly are swap rates and why are they so important?

The move from Variable to Fixed Rate Mortgages

Next year marks 30 years since the Bank of England became independent from Government control, a change that reshaped how interest rates are set in the UK. Today, interest rates are decided by the Monetary Policy Committee (MPC) nine specialists who meet roughly every six weeks. After two days of discussion, they announce their decision at 12pm on a Thursday.

Years ago, most mortgage borrowers were on standard variable rates, meaning any change in interest rates hit their monthly payments immediately. The interest you paid was set at a particular point over and above the base rate – the Bank of England’s headline rate of interest. But things have changed.

More than 80% of new UK mortgages are now on fixed‑rate products, giving borrowers stability and protection from sudden rate rises. Your payment stays the same even if the Bank of England moves rates up or down. This means that the vast majority of mortgages are no longer as closely tied to the Bank of England’s headline rate. So if this no longer directly sets mortgage rates, what does? The answer: swap rates.

How do swap rates work?

Swap rates are the hidden engine behind fixed‑rate mortgages. They’re the rates at which lenders “swap” their exposure to interest rate changes effectively locking in the cost of money for 2, 3, 5 or even 10 years.

Think of it like this – a lender says: “We want to borrow money for 5 years, but we don’t want the cost to jump around. We want it fixed.” Another financial institution replies: “We’ll swap with you – you give us a variable rate, and we’ll give you a fixed rate.” The fixed rate they agree on is the swap rate.

Swap rates move based on:

• Inflation expectations
• Market predictions of future Bank of England decisions
• Global financial conditions
• Lender funding costs
• Investor demand for long‑term fixed returns

Swap rates are basically the financial market’s best guess of where interest rates will be over the next 2, 3, 5 or 10 years.

Why mortgage borrowers should care about swap rates

Why mortgage borrowers should care about swap rates

Swap rates matter because your fixed‑rate mortgage is priced on top of them. And because of this, they will influence some pretty important factors when it comes to taking out a mortgage – whether it is worth waiting or acting now, when you can lock in a cheap 5-year fixed, whether lenders suddenly pull products and whether remortgaging in general becomes more expensive.

Ultimately, if swap rates go up, fixed mortgage rates go up. If swap rates fall, fixed mortgage rates fall. Even if the Bank of England does nothing, swap rates can move and lenders adjust fixed rates immediately.

Swap rates move daily, sometimes hourly long before the Bank of England announces anything. This is why you sometimes see headlines like: “Mortgage rates rise despite no change in Bank Rate.” It’s because swap rates have moved, not the Bank of England.

If you have a fixed rate mortgage or are looking to get one, knowing that it is the swaps rate not the Bank of England base rate that really determine your options will allow you to make a more informed decision.