Can You Overpay a Mortgage During a Fixed Rate Period? (UK)
- Nick Parker
- Jan 11
- 3 min read
Updated: Jan 12
Summary
This article explains how mortgage overpayments work during fixed-rate periods in the UK, including early repayment charges, lender rules, and common limitations. It is for general information only.
If you’re on a fixed rate mortgage, you may be wondering whether you’re allowed to overpay — and if doing so could trigger early repayment charges.
The good news is that most UK lenders do allow overpayments during a fixed rate period, but there are rules and limits you need to understand to avoid unnecessary fees.
In this guide, we explain how fixed rate overpayments work, what restrictions apply, and how to plan overpayments safely.
Can you overpay during a fixed rate mortgage?
Yes — in most cases, you can overpay during a fixed rate period, but only up to your lender’s annual overpayment allowance.
For many UK mortgages, this allowance is typically:
Up to 10% of your outstanding balance per year, penalty-free
Any overpayments above this limit may trigger early repayment charges (ERCs).
If you’re not sure how this allowance works, we explain it in detail in our guide on
Why do fixed rate mortgages have overpayment limits?
Fixed rate mortgages are priced based on an assumption that the loan will remain in place for a set period.
When borrowers repay too much too early, lenders may:
Lose expected interest income
Incur funding costs
Overpayment limits help lenders balance flexibility with predictable returns — while still giving borrowers room to reduce debt.
What happens if you exceed the overpayment allowance?
If you overpay more than your permitted allowance during a fixed rate:
An early repayment charge may apply
ERCs are usually calculated as a percentage of the excess amount
Charges typically reduce as you approach the end of the fixed term
In some cases, paying an ERC may still make financial sense — but it’s important to calculate this carefully.
👉 You can estimate interest savings using our free mortgage overpayment calculator before committing.
Monthly overpayments vs lump sums during a fixed rate
Both monthly overpayments and lump sums usually count toward your annual allowance.
For example:
£400 per month = £4,800 per year
£8,000 lump sum later in the year
Total overpayments = £12,800
If your allowance is £25,000, you’d still be within limits — but tracking cumulative payments is essential.
This is where longer-term planning becomes valuable.
Is it worth overpaying during a fixed rate period?
Often yes — but it depends on:
Your interest rate
Your remaining fixed term
Whether you have higher-interest debt
Alternative uses for spare cash
We explore the broader pros and cons in more detail in is overpaying your mortgage worth it in the UK?
Fixed rate overpayments vs saving the money instead
Some borrowers choose to save during a fixed rate period and overpay later — particularly if savings rates are competitive.
This approach can:
Preserve liquidity
Avoid breaching overpayment caps
Provide flexibility at remortgage time
We compare these strategies fully in
[mortgage overpayments vs savings accounts].
What happens when your fixed rate ends?
Once your fixed rate ends:
Overpayment restrictions are often removed
You may be able to overpay freely on a variable rate
Remortgaging can reset allowances
Planning overpayments around this transition can significantly improve outcomes.
👉 The Advanced Mortgage Planner lets you model overpayments before and after your fixed rate ends, helping you time payments more effectively.
How to plan fixed rate overpayments safely
To avoid charges:
Check your lender’s overpayment allowance
Track total overpayments across the year
Spread payments where possible
Review terms annually
Small, consistent overpayments within your allowance can still save thousands in interest.
Final thoughts
Overpaying during a fixed rate mortgage is usually allowed — but only within defined limits.
Understanding those limits, and planning around them, can help you:
Reduce interest
Shorten your mortgage term
Avoid early repayment charges
A few minutes of planning can make a meaningful difference to your long-term finances.
