Is it better to put a little extra towards your mortgage each month or pay a lump sum when you can? There is no universal winner. How much you pay, how early you pay it, and what your lender does afterwards all affect the result.
The key difference is timing
Mortgage interest is generally calculated on the outstanding balance. Reducing that balance sooner can reduce subsequent interest, assuming the lender applies the overpayment to the capital. A lump sum reduces the balance in one go; monthly overpayments reduce it gradually. Both may help, but they are not directly comparable unless you consider the total extra amount paid.
A fairer £5,000 comparison
Imagine you have £5,000 available for extra mortgage payments. You could pay the £5,000 today, or spread the same £5,000 over 50 months at £100 a month. This compares the same total contribution, but not the same payment timing.
| Approach | Extra amount | When it reduces the balance |
|---|---|---|
| One-off lump sum | £5,000 | Immediately, if accepted and applied |
| Monthly overpayments | £100 × 50 months = £5,000 | Gradually over four years and two months |
With the same starting mortgage, unchanged rate and no charges, the earlier £5,000 payment would typically reduce more interest over that period, because the balance is lower sooner. That does not automatically make it the right option: keeping accessible savings and avoiding penalties can matter more than the illustrative interest difference.
What if you do not have £5,000 ready?
Then the comparison changes. Regular overpayments might be achievable from monthly surplus income, while saving up for a lump sum delays when the mortgage balance falls. If you need an emergency cash buffer, using all your savings for a mortgage overpayment can leave you short of accessible money.
Three lender details that can change the answer
- Overpayment allowances: some mortgage deals limit penalty-free extra payments, often by reference to a yearly allowance. Check your own agreement.
- Early repayment charges: going beyond the allowance, or paying during a restricted period, may trigger charges.
- What happens to your monthly payment: your lender may reduce the monthly payment, shorten the term, or ask you to choose. A calculator assuming unchanged regular payments can give a different result from a lender that recalculates them.
How to compare your own scenarios
- Enter your remaining balance, interest rate and remaining term in the free mortgage overpayment calculator.
- Try an extra monthly payment, such as £100.
- Then test a one-off lump sum, such as £5,000, and note the timing and total amount contributed.
- Compare estimated interest and payoff dates, then check the lender's actual terms and your need for accessible savings.
Compare monthly and lump-sum overpayments →
Common questions
Is a £5,000 lump sum the same as £100 a month?
Only after 50 monthly payments have been made. The lump sum reaches the mortgage earlier, so the interest effect may differ even though the total paid is the same.
Will overpaying always shorten my mortgage term?
Not necessarily. Your lender may instead recalculate your regular payment. Check how your mortgage handles overpayments.
Can I make both types of payment?
Some mortgage products permit both within their terms and allowances. Check with your lender before paying.
UK-focused general educational information. Illustrations assume a repayment mortgage and do not account for every lender rule, changing interest rate or fee. Not personal financial advice. Related reading: Is £100 extra a month worth it?
