The Fixed-Rate Cliff: What Happens When Your UK Mortgage Deal Ends

Most UK mortgages are fixed only for a deal period, typically two or five years, sitting inside a much longer overall term, not for the life of the loan. When that deal period ends, the mortgage doesn't disappear or renew automatically at a similar rate. It rolls onto the lender's standard variable rate (SVR), and for a lot of borrowers that's the moment a manageable mortgage becomes a genuinely stressful one.

What actually happens the day your deal ends

Nothing dramatic on paper — no letter demanding a lump sum, no default. Your mortgage simply switches, usually the day after your fixed or tracker deal expires, onto your lender's SVR: an interest rate the lender sets itself and can change more or less whenever it wants, subject only to giving you notice.

SVRs sit well above the fixed rates lenders offer to new or remortgaging customers, because the SVR book is largely made up of borrowers who haven't shopped around, so lenders face limited competitive pressure to keep it low. As of mid-2026, average UK SVRs sit around 7.13%, with individual lenders ranging from roughly 6.31% to 8.38%. Compare that to the two-year fixed rates being advertised to new customers, typically in the 4-5% band, and the gap is substantial.

A worked example

Take a borrower with £250,000 remaining on their mortgage and 25 years left to run, coming off a two-year fixed deal at 4.5%.

• On the fixed rate (4.5%): monthly payment of roughly £1,390
• Rolling onto the average SVR (~7.13%): monthly payment of roughly £1,788

That's an increase of about £398 a month (a jump of roughly 29%) — for no reason other than the calendar. Nothing about the borrower's risk profile changed; the deal period simply ran out.

Why this used to be called an "affordability cliff" and no longer legally is

Until August 2022, the Bank of England required lenders to stress-test new mortgage applicants against a rate 3 percentage points above the lender's own SVR, specifically to make sure that if a borrower did revert to the SVR, they could still afford the higher payment. That mandatory affordability buffer was withdrawn in 2022, on the reasoning that the FCA's existing affordability rules (under MCOB 11.6) and structurally higher rates already provided enough of a check.

The practical effect: lenders now set their own stress-test margins rather than following a central-bank-mandated number, and those margins vary by lender and by product. It doesn't remove the SVR cliff itself, since that's a structural feature of how UK mortgages are built. It just changes who decides how much buffer to test for. (See our comparison of how mortgage stress tests work across the UK, US, Canada and Australia.)

How to avoid landing on the SVR by accident

The single most common mistake is waiting until the deal ends to start looking for a new one. In practice:

• Start shopping 3-6 months before your deal expires. Most lenders let you lock in a new rate that far ahead and won't charge you for switching before the old deal actually ends.
• Check for early repayment charges (ERCs) before switching early. If your current deal still has time left and carries an ERC, moving early might cost more than it saves, so run both numbers.
• Consider a "product transfer": staying with your existing lender on a new deal, versus a full remortgage to a new lender. Product transfers are usually faster and involve less underwriting, but a new lender might offer a meaningfully better rate.
• Model the SVR scenario deliberately, even if you're confident you'll remortgage in time. Deals fall through, life circumstances change, and knowing your worst-case payment in advance means it's never a surprise.

Timing is the whole fix

The "cliff" isn't a design flaw so much as the mechanical consequence of how UK mortgage deals are structured: a short, competitively priced fixed period sitting inside a long-term loan, with an expensive, lender-set default rate waiting at the end of it. The fix comes down to timing. Borrowers who start shopping for their next deal months before the current one ends essentially never experience the cliff at all; they simply move from one competitive rate to the next.