If a much cheaper deal is available but you're tied to a fix, this calculator tells you how many months until a remortgage pays for itself, Early Repayment Charge and fees included.
What you're paying now.
If break-even is quicker than your remaining fix period, stay put. If it's longer than the new fix you'd lock into, switching is a gamble.
Remortgaging mid-fix is expensive. You pay the Early Repayment Charge on your current deal, plus product fees and legal costs on the new one. The question is whether the monthly saving on the new rate pays that back fast enough to be worth the trouble.
The break-even maths is straightforward: add the ERC (typically 1–5% of your outstanding balance) plus any fees on the new deal (£500–£1,500 is typical). Divide that total by your monthly saving on the new rate. The answer is how many months it'll take before you're ahead.
If that number is shorter than the months left on your current fix, switching makes sense. If it's longer, you're usually better off waiting.
Many fixed-rate deals are "portable", you can take them with you if you move home within the fix period, rather than paying the ERC. Ask your lender before assuming you're stuck.
Even if the break-even is marginal, switching gives you immediate monthly cash-flow relief. That matters more to some households than others. If a 5.5% rate is stressing your budget, moving to 4.2% today has non-financial value you won't see in the calculator.
If the break-even looks favourable, a whole-of-market broker can usually match or beat the rate you found. The FCA has a consumer guide to mortgages covering what to watch for, and MoneyHelper's remortgage page explains the process end-to-end.
See the LTV threshold calculator, dropping an LTV band before you remortgage can unlock significantly cheaper rates, which changes the break-even equation completely. Also worth checking your lender's specific ERC schedule rather than using a generic estimate.