How Much Does Overpaying £100/Month Save?

On a £250,000 mortgage at 4.5% over 25 years, overpaying by £100 per month could:

• Save approximately £22,000 in total interest
• Reduce your mortgage term by around 3 years
• Give you a new payoff date roughly in 2048 instead of 2051

That's £100/month in, but £22,000 back over the life of the mortgage — an effective return far exceeding most savings accounts.

The impact scales with your balance. On a £400,000 mortgage at the same rate, the same £100/month overpayment saves roughly £30,000 in interest.

Most UK lenders allow overpayments up to 10% of your balance per year without penalty. £100/month on a £250,000 mortgage is well within this limit (around 0.5% of balance annually).