People wanting to maximise their state pension by plugging gaps in their National Insurance record have contributed to a total of 68,673 years, worth £35m, since April last year, HMRC said.

People only have until 5 April to check their NI record and fill any gaps from the previous 20 years, from 6 April 2006 onwards.

From 6 April, people will only be able to make voluntary NI contributions for the previous six tax years, in line with normal time limits.

Angela MacDonald, HMRC’s second permanent secretary and deputy chief executive, said: “There are just two months left to check and fill any gaps in your National Insurance record from 2006 onwards to boost your state pension entitlement.”

Since the launch of HMRC’s enhanced digital service last April, more than 4.3million people have used it to check their state pension forecast. People can also use it to check and view gaps in their NI record, calculate the difference any payment will make to their state pension and then make one payment for however many years they need to top up.

HMRC said that more than 37,000 online payments have been made through the service since last April and two thirds, 65%, of the years topped up by customers are from 2017 onwards.

HMRC said the average online top-up payment is £1,835 and the largest weekly State Pension increase is £113.76.

Rosie Hooper, Chartered Financial Planner at Quilter Cheviot, said: "The scale of uptake highlights the importance of this scheme, particularly given that from April 2025, individuals will only be able to backdate contributions by the usual six years. This means that many people who might otherwise miss out on thousands of pounds in state pension entitlement have only a short window left to take action.”

She pointed that that some top-ups have resulted in a weekly pension increase of as much as £113.76, equating to an annual increase of £5,915.92.