Mortgage overpayments are exceeding £9 billion each year, according to new research from Santander Mortgages.

Its research shows that 19% of those with a mortgage currently overpay every month. These 2.5 million people each overpay an average of £181 every month, meaning they are collectively paying an additional £455 million on top of their standard mortgage repayments on a monthly basis.

Another 6% tend to make a one-off overpayment on their mortgage once a year and a further 9% don’t regularly overpay but have done so once in the past 12 months. Those who have made a one-off overpayment in the past year (nearly two million people) overpaid an average of £1,919.

In total, 34% of those with a mortgage make some form of overpayment, whether monthly or via one-off payments.

Santander said its findings reveal that many have started overpaying in recent months and years, to take advantage of low interest rates. 13% of those who overpay every month started doing so in the past six months, 24% within the last year and 54% within the last two years.

However, 23% of Britons with a mortgage have no idea if their mortgage provider allows overpayments at all and a further 14% say their provider allows overpayments but aren’t sure if they charge for them. Another 8% say their mortgage provider definitely charges customers for making overpayments.

Phil Cliff, director of Santander Mortgages, said: “If you overpay on your mortgage you will pay less interest over the full term, so it’s a good thing to do if you can afford to.

“Nearly half of those people who have never overpaid on their mortgage still put money into savings each month, and given the average interest rate on these people’s savings accounts is just 1.6%, in the long-term they may be better off using this money to make mortgage overpayments instead.”