It just got easier to top up your state pension — but should you?

Filling in gaps in your national insurance record is an easy way to boost your state pension income — but getting it wrong could leave you out of pocket.

Some have complained of handing over thousands of pounds to HM Revenue & Customs (HMRC) only to find that it has had no effect on their state pension. Fewer people should fall into that trap now though — since Monday a new online service allows you to top up easily, and only when it is worth your while.

“The state pension is the foundation of income in retirement,” Paul Maynard, the pensions minister, said. “I would encourage everyone to check their state pension forecast and to take a look at how they could improve it with only a few simple clicks.” Here’s what you need to know.

How does it work?

You need 35 years of national insurance contributions to get the new full state pension, which pays up to £221.20 a week (£11,502 a year) and is guaranteed to go up each year in line with average wages, inflation or by 2.5 per cent, whichever is higher. Those who retired before April 2016 and get the old basic state pension need 30 years of contributions to get the full amount.

You may have gaps in your record for times when you were unemployed, worked abroad or received certain benefits. Normally you can fill in only gaps from the previous six tax years, but until April 2025 those who are entitled to the new state pension can fill in gaps going back to April 2006. The Sunday Times has called for a permanent right to fill in ten years of missing payments.

It typically costs about £824 to fill in a missing year, and this could boost your state pension by almost £329 a year at today’s rates. That’s equivalent to £6,573 over a 20-year retirement. Once you have made a payment you need to wait for your record to be updated.

“But getting your record updated by HMRC is only half of the story,” said Steve Webb, a former pensions minister who is a partner at the consultancy Lane Clark & Peacock. “It then needs the Department for Work & Pensions [DWP] to reassess your state pension entitlement based on your improved contribution record. There are already too many cases where people wait months or longer.”

• Will you have to pay tax on your state pension?

How has the system changed?

Under the new online system most people below state pension age can work out whether filling in gaps is worthwhile by logging into their personal tax account online through the gov.uk website or HMRC app. You can pay voluntary national insurance contributions online or by bank transfer without needing to speak to someone over the phone. This has replaced a two-stage phone process where customers who had not reached state pension age first had to speak to the Future Pension Centre to check which years were missing and whether filling in the gaps was worthwhile. They would then be transferred to HMRC to get the details of how to make the payment.

Last year the window for filling in missing years of national insurance going back to 2006 was due to close, and customers complained of long delays getting through on the phone. The government has since extended the deadline twice.

The online service is not available to those who already get the state pension or to people who are self-employed, living outside the country or have gaps in their employment history because they worked abroad. If you already get the state pension you should call the Pension Service on 0800 7310469 to fill any gaps.

• What is the state pension triple lock?

Are top-ups always a good idea?

Filling in gaps in your record will not always boost your state pension. If you were contracted out of getting the additional state pension, for example, and paid a lower rate of national insurance contributions during your working life, paying to fill in gaps before 2016 may not benefit you.

“The system is complicated. It’s close to impossible for most people to track and understand,” said Tom Selby from the investment platform AJ Bell. “It is important to double-check whether you will benefit before handing over any money. It may be worth speaking to a financial adviser.”

If you paid to fill in gaps in your national insurance record then found that your state pension has not increased you might not be able to get your money back. You can apply for a refund through gov.uk, but it is up to HMRC to decide whether to give you one. If you can show that you were given the wrong advice by a government service or department that could help your case.

“It is vitally important to keep records of any phone conversation with HMRC or the DWP in case you later need to provide evidence of what you were told. Although these calls are normally recorded you should keep your own record too,” Webb said.

HMRC said that the new online system will only give you the option of filling in missing years of contributions if doing so will boost your state pension.

Can I fill in gaps for free?

You may be eligible for national insurance credits to fill in gaps, and may be able to claim for credits backdated over years, so it is worth finding out what you are entitled to.

Credits are available if you claim benefits because of ill health or unemployment, are on maternity or paternity leave, are looking after a child under the age of 12 or are married to someone in the armed forces and accompany them on a posting overseas. Grandparents who look after their grandchildren could be entitled to credits if a parent or carer getting child benefit transfers them their credit. Find out more at gov.uk.