Switching mortgage deals before your current fixed period ends can save real money — or cost real money — depending on one number most borrowers never check until they need it: the early repayment charge (ERC) written into their existing mortgage offer.
How ERCs Are Typically Structured
Most UK fixed-rate mortgages carry an ERC that declines on a sliding scale across the fixed term — commonly something like 5% of the balance in year one, stepping down by roughly one percentage point each year until the fix ends. A 5-year fix might carry charges around 5%, 4%, 3%, 2%, 1% across its five years, though the exact scale varies significantly by lender and product — this is written into your original mortgage offer document, not a universal industry standard.
Worked Example
A borrower with a £262,500 balance, two years into a 5-year fix with a declining ERC schedule (5%/4%/3%/2%/1%), currently in year 3 (3% charge):
| Item | Amount |
|---|---|
| Remaining balance | £262,500 |
| Current ERC rate | 3% |
| Early Repayment Charge | £7,875 |
Against that charge, compare the savings from switching. If current rates have dropped enough that a new deal saves £120/month over the remaining term, and there are still 24 months left on the old term, that's roughly £2,880 in savings — not enough to clear a £7,875 penalty. If the rate gap is larger, or more time remains on the term, the math can flip decisively the other way.
Remortgage vs. Product Transfer
These are genuinely different moves. A remortgage means switching to a new lender entirely — full underwriting, a new valuation, and typically legal work, but access to the whole market. A product transfer means staying with your existing lender and simply moving onto a new rate — usually faster, cheaper, and without full re-underwriting, but limited to whatever deals your current lender is offering, which may not be the market's best rate.
Common Mistakes
Borrowers frequently calculate whether switching is worth it by comparing rates alone, without factoring in the ERC, valuation fees, and legal costs that come with a full remortgage — a product transfer often has a much lower breakeven point specifically because most of those costs don't apply.
Borrowers also wait until their fix has already ended to start looking, missing the window to lock in a new rate in advance and lapsing onto the lender's standard variable rate for a period in between — often the most expensive outcome available.
A third mistake: assuming the ERC applies to the whole mortgage even on a partial overpayment. Most lenders allow a set annual overpayment allowance (commonly 10% of the balance) penalty-free — the ERC applies to amounts beyond that allowance, or to a full early exit, not routine overpayments within the limit.
Where This Tool Has Limits
It uses an abrasive, common ERC structure — your actual mortgage offer document has the specific percentages and schedule that apply to your loan, and these vary meaningfully by lender and product. It also can't factor in whether your financial circumstances (income, credit, employment) have changed enough since your original mortgage to affect what a new lender would actually offer you.
Frequently Asked Questions
Can I avoid the ERC entirely by waiting?
Yes — ERCs only apply if you exit before the fixed term ends; waiting for natural expiry (or arranging a new deal to start right after) avoids the charge altogether.
Is a product transfer always cheaper than a full remortgage?
Usually in terms of fees and process, yes, but it limits you to your existing lender's current offers — worth comparing against the wider market before deciding.
How far in advance can I lock in a new rate?
Many lenders allow rate reservations 3-6 months before your current deal ends, letting you secure a new rate without an ERC and without a gap on the lender's SVR.
Does overpaying within my allowance affect my ERC if I remortgage later?
No — allowance-based overpayments reduce your balance (and therefore future interest), but don't change the ERC percentage that applies if you fully exit before term end.
What happens if my fix ends and I do nothing?
You roll onto the lender's standard variable rate automatically — usually the most expensive option, and one product transfer or remortgage timed in advance is designed to avoid.
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Educational content, not financial advice. ERC structures and remortgage costs vary significantly by lender and mortgage product — confirm your specific terms in your mortgage offer document or with a licensed UK mortgage adviser. Written by the MortgagePro Global team.