Homeowners are being warned not to delay renewing a mortgage deal after Nationwide Building Society become the latest major lender in the UK to lift rates.As bond yields have risen this past few weeks, swap rates have climbed – the financial product from which mortgage prices are derived. It signals that the Bank of England could be in a position lift the base rate in the coming months.While governor Andrew Bailey has clearly stated there is no pre-determined arrangement to raise interest rates, multiple factors are pushing inflation higher – primarily energy costs prompted by the Iran War. That may lead to higher interest rates, which would send mortgage products like tracker mortgages up in cost for homeowners.But other homeowners are on fixed-term deals, often for two or five years for example, and those products have been lifted this week by a range of major high street lenders, including Halifax, Barclays, Santander and HSBC – highlighting the need for people needing a new deal to act fast before further rises.Jamie Alexander, mortgage director at Alexander Southwell Mortgages, said Nationwide’s move makes it more likely that others may soon follow.“When a lender the size of Nationwide moves rates up, the rest of the market pays attention,” he said. “This is not a surprise given where swap rates and gilt yields have been heading, but it is another blow for borrowers who were hoping the worst was behind them.“The honest message right now is do not wait. Securing a rate today and reviewing it if things improve is a far safer position than sitting on the fence hoping for something better that may not come.“The window on today's deal does not stay open. For anyone coming off a fixed rate in the next six months, start the conversation now.”Get a free fractional share worth up to £100.Capital at risk.Terms and conditions apply.Go to websiteADVERTISEMENTGet a free fractional share worth up to £100.Capital at risk.Terms and conditions apply.Go to websiteADVERTISEMENTCraig Fish, of Lodestone Mortgages, gave the same warning. “For borrowers, the message is simple – rates are more likely to drift up than down from here, so anyone with a deal expiring in the next six months should be locking something in now. “Sitting on your hands in this market is the expensive option.”For Nationwide, their rate increase applies across First Time Buyer, Home Mover, Existing Customers Moving Home and Remortgage products along with Switcher and Additional Borrowing deals. Both fixed and tracker rates have moved upwards by up to 0.2 per cent.Moneyfacts data shows that on 10 September, the average two-year fixed residential mortgage rate is 5.67 per cent, with a five-year fix slightly higher at 5.71 per cent.However, the average two-year tracker rate is 4.52 per cent. This type of mortgage has seen an uptick in people switching to them, some mortgage brokers have previously confirmed to The Independent.Those are the ones – along with anyone on a lender’s Standard Variable Rate, which is usually more expensive – which would be affected in the event of the BoE voting to raise (or lower) interest rates, increasing their monthly costs accordingly. The base rate is currently 3.75 per cent, with the next vote taking place on 17 September.Perhaps wisely given how markets have been moving, the data does suggest people are making the move as soon as they can. FCA numbers show more than 880,000 people renewed their deal up to six months before it came to an end during the first half of 2026 , though a similar number need to do so in the coming months, too, with their deals expiring before the end of the year.“Nearly a million borrowers took advantage of measures included in the FCA’s mortgage charter to proactively manage their mortgage costs by locking in a new deal up to six months ahead of maturity in the first half of 2026,” confirmed Damien Burke, head of regulatory practice at credit advisory firm Broadstone.“With mortgage rates beginning to rise again, borrowers approaching the end of fixed-rate deals should consider their options early so that they are able to secure the best rates available to them.”