The quick answer
You don't need a bonus or an inheritance to pay your mortgage off faster. An extra £50 or £100 a month, paid consistently, can cut years off your loan and save you thousands of pounds in interest. Your lender won't tell you how much you could save. This article will.
Why a little extra goes so far
Every month, your payment does two jobs: it pays the interest that built up on what you owe, and it pays off some of the balance. In the early years, most of your payment goes on interest.
An overpayment is different. All of it goes straight off the balance. A smaller balance means less interest next month, so a bit more of your normal payment goes on the balance too. That keeps repeating every month until the loan is gone. That's why small amounts add up to far more than the money you put in.
What it looks like in numbers
Take a typical UK mortgage: £200,000 over 25 years at 4.5%. The monthly payment is about £1,112, and over the full term you'd pay roughly £133,500 in interest.
Here's what a small extra each month does:
| Extra each month | Interest saved | Mortgage-free sooner by |
|---|---|---|
| £25 | £6,044 | 11 months |
| £50 | £11,534 | 1 year 10 months |
| £100 | £21,142 | 3 years 6 months |
| £200 | £36,281 | 6 years 1 month |
£200,000 repayment mortgage, 25 years, 4.5% fixed for the whole term.
At £100 a month you'd put in about £25,700 extra in total and save over £21,000 in interest. So each extra pound saves you about 82p, and you're free three and a half years sooner.
It works at other sizes too. On a £300,000 mortgage over 30 years at 4%, an extra £100 a month saves about £28,750 and takes 3 years 6 months off. On a £25,000 personal or car loan over 5 years at 8%, the same £100 saves about £1,100 and finishes 11 months early.
Consistency beats size: start now
The timing matters as much as the amount. On the same £200,000 mortgage, an extra £100 a month saves:
- £21,142 if you start straight away
- £12,721 if you wait 5 years
- £6,721 if you wait 10 years
Waiting five years costs you over £8,000. Early overpayments go to work on the biggest balance and get the most years to compound. A small amount you can keep up beats a big amount you'll stop after six months.
Monthly top-ups or a yearly lump sum?
Both work. On our example, £100 a month saves £21,142, while £1,200 paid once a year saves £20,256. Paying monthly comes out slightly ahead because the money starts cutting the balance sooner. If your income is lumpy (bonuses, freelance work, tax refunds), a mix of the two is fine. The best plan is the one you'll actually stick to.
Before you overpay: five checks
- Check for early repayment charges. Many UK fixed and tracker deals let you overpay up to 10% of the balance a year without a fee. Go over that and you could pay a charge. Check your mortgage offer or ask your lender.
- Keep an emergency fund first. Money you've overpaid is usually hard to get back. Keep a few months of spending in easy-access savings before you start.
- Clear more expensive debt first. Credit cards and overdrafts usually cost far more than a mortgage, so pay those off first.
- Compare with your savings rate. If savings pay more after tax than your loan costs, saving may win for now. When your loan rate is higher, overpaying is a guaranteed, tax-free return.
- Choose a shorter term, not a lower payment. After an overpayment, some lenders lower your monthly payment instead of shortening the term. To save the most interest, ask them to keep your payment the same and shorten the term.
In the US? Most mortgages there have no prepayment penalty. When you send extra money, make sure your servicer applies it to the principal.
Make it a habit, not a one-off
The hard part isn't the maths. It's sticking with it. A few things help:
- Automate it. Set up a standing order the day after payday, so you never see the money.
- Round up. Paying £1,150 instead of £1,112 hardly feels different, but it's £38 a month off your balance.
- Raise it with your pay. Each time you get a pay rise, add a slice of it to your overpayment.
- Watch your progress. Seeing how much interest you've already saved is what keeps people going.
How GoLoanly helps
I built GoLoanly because I was planning overpayments on my own loan in spreadsheets, and they never told me what I really wanted to know. GoLoanly isn't another loan calculator. It's built around three things:
- Understand: the AI Coach. Ask about your loan in plain words. The Coach suggests strategies that fit what you can spare, and you apply one to your plan in a tap. Every figure comes from GoLoanly's own calculations, not the AI.
- Plan: compare strategies side by side. £50 a month, £100 a month, a yearly lump sum: see them all on one chart, with the payoff date, time saved, interest saved and the total you'll pay for each. Keep the one that fits your budget.
- Stay on track: reminders. A heads-up a week before each lump sum, an update on the interest you've saved every three months, and a check-in every two months to keep your plan up to date.
To add a loan, you can fill in the form in the app, or import a CSV schedule, or let AI read your loan statement PDF. You can then see all your loans in one place.
The calculator and reminders are free, work offline and need no account, with up to 5 loans and 3 custom strategies each. GoLoanly Plus makes plans, strategies and AI Coach questions unlimited and adds PDF and Excel export and a monthly AI review by email.
Go overpay your loan. Save thousands.
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Questions
How much does overpaying £100 a month save?
On a £200,000 repayment mortgage over 25 years at 4.5%, an extra £100 a month saves about £21,142 in interest and clears the mortgage 3 years and 6 months early.
Is it better to overpay monthly or with a yearly lump sum?
Both work. On the same mortgage, £100 a month saves £21,142 and £1,200 once a year saves £20,256. Monthly comes out slightly ahead because the money starts reducing the balance sooner.
Are there fees for overpaying a mortgage?
Many UK fixed and tracker deals let you overpay up to 10% of the balance a year without a fee; above that, an early repayment charge may apply. Check your mortgage offer or ask your lender. Most US mortgages have no prepayment penalty.
This article is general planning information, not financial advice. Figures are illustrative, worked out with GoLoanly's own calculations, and assume a fixed rate for the whole term. Your lender's terms and your own situation come first.