Most UK mortgages are taken out on a 2, 5 or 10-year fix. When that fix ends, your mortgage doesn't end, but the deal you agreed to does. Three things can happen next, and only one of them is actively chosen. The other two are what happen when you don't act. If you're within 12 months of your fix ending, this guide walks you through exactly what to do, when, and why timing matters.
What's actually happening, in plain English
When you took out your fix, you agreed an interest rate that was locked in for a set period, say 4.99% for 2 years. During that period, your monthly payment didn't change even if the Bank of England moved base rate. Once the fix ends your payment changes, you can estimate the new figure with the mortgage repayment calculator.
On the day your fix ends, that locked-in rate disappears. The mortgage continues, same balance, same property, same lender, but the interest rate now defaults to your lender's Standard Variable Rate (SVR) unless you've arranged something else.
The mortgage doesn't end. Your relationship with this specific deal does.
The three options in front of you
When your fix ends, you have three routes, only the first two are actively chosen:
- 1. Remortgage to a new lender. Apply for a brand new mortgage with a different lender. They pay off your existing one. You get whatever rate that new lender offers, usually competitive because they're trying to win your business.
- 2. Product transfer with your existing lender. Stay with the same lender but switch onto one of their current deals. Less paperwork, no new affordability check, usually quicker.
- 3. Do nothing. Your mortgage automatically rolls onto SVR, typically 2-3% higher than competitive fixed deals. This is the default if you ignore the letters from your lender.
Why doing nothing is so expensive
SVR in mid-2026 is typically 7.5%-9% across major UK lenders. Compare that to current best buys around 4.3%-5.5%.
On a £200,000 mortgage, the gap looks like this:
Every month on SVR vs a competitive fix is roughly £250-£500 of avoidable interest. Over six months of inaction, that's £1,500-£3,000. The number that catches people out is how fast it adds up while they 'mean to sort it'.
- On SVR at 8%: roughly £1,544/month interest-only equivalent.
- On a 5-year fix at 4.8%: roughly £1,144/month interest-only equivalent.
- Difference: £400/month, or £4,800/year.
When to start acting, the 4-6 month window
You can usually secure a new rate 3-6 months before your current fix ends. Most lenders 'pipeline' the offer, they hold it for you, and your new rate kicks in automatically the day the old one expires.
That's the sweet spot. You're not committed yet (you can usually still cancel before completion), but you've locked in a rate. If rates fall before completion, many lenders let you switch to the better deal. If rates rise, you've protected yourself.
Remortgage vs product transfer: which is better?
Both work. The right one depends on your situation:
Most borrowers benefit from remortgaging, it tends to find a better rate. But if your circumstances have changed (income drop, recent credit issues, becoming self-employed in the last 12 months), a product transfer might be the only option a lender will accept. Worth having a broker look at both. For a deeper comparison, see our full product transfer vs remortgage guide. One timing point worth knowing: a remortgage offer usually lasts about six months, whereas most lenders only let you book a product transfer three to four months before your deal ends. I explain the lender-by-lender windows in my guide to how product transfers work.
- Remortgaging usually finds the best rate because different lenders compete for your business. Downside: full application process, takes 6-8 weeks, conveyancing fees (often paid by the new lender via cashback).
- Product transfer is faster (a few weeks), no conveyancing, no affordability check in most cases. Downside: limited to your existing lender's current deals, you might be leaving money on the table.
What to do if your circumstances have changed
If something has shifted since you took out the original mortgage, your income dropped, you've gone self-employed, you've had a credit blip, you've had a baby and your outgoings increased, these affect what you can do next.
Product transfer with your existing lender is usually still available, even if your new affordability would fail at a new lender. Lenders generally don't reassess affordability when you product transfer, they just need to confirm you're still meeting payments. This is one of the situations where staying put is genuinely the best option.
Should you use a broker?
A whole-of-market broker compares your existing lender's product transfer rates against the wider market and tells you which is genuinely best. Without one, you're either taking your lender's offer at face value (they have no incentive to give you their best rate) or DIY-ing comparison sites that don't include every lender or every deal.
How a broker is paid varies. The new lender pays the broker a procuration fee, and many brokers also charge their own fee for arranging a remortgage, so it is worth asking upfront what you will pay and what it covers. A good broker will always be clear about that before you commit to anything.
The single most expensive mortgage mistake in the UK is letting a fixed rate quietly roll onto SVR. The fix? Start the conversation 4-6 months before your deal ends. Debbie at DS Financial tracks deal expiry dates for every client and reaches out months in advance, so the switch happens cleanly and SVR never becomes an issue. If you'd like that done for you, a no-pressure chat costs nothing.
General information, not financial advice. Your home may be repossessed if you do not keep up repayments on your mortgage.
Sources: MoneyHelper, Remortgaging, FCA, Switching mortgages, UK Finance, Mortgage data.
Stage 9, After you have moved in
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