The Department for Work and Pensions has admitted that most of those who are owed thousands of pounds due to large-scale errors in the state pension system will not be reimbursed.

The government has been accused of abandoning more than 100,000 parents and carers, mainly mothers, who were affected by errors in their national insurance record that reduced their state pension.

Workers need 35 full years of national insurance contributions to qualify for the full new state pension, and ten years of contributions to qualify for anything at all.

Parents who claimed child benefit between 1978 and 2010 should have been given Home Responsibilities Protection, which would have given them a credit on their national insurance record and boosted their state pension entitlement.

But widespread system errors meant many parents who claimed child benefit before 2000 did not get their national insurance credits and so are owed state pension, in some cases as much as £4,500 a year. The government has said that the issue mostly affects stay-at-home mothers now in their sixties and seventies.

In 2023 the DWP began writing to those it thought may be missing the protection from their national insurance record, inviting them to make a claim and rectify any arrears. HM Revenue & Customs, the department responsible for national insurance, wrote to 370,000 people, including 257,000 who were already over state pension age. This correction exercise ended in April 2025.

Last year the DWP estimated it would be able to reach and correct the records of 90 per cent of people owed state pension — but this week it reduced this to 8 per cent.

• Stay-at-home mums bore the brunt of £1bn pension blunder

It means that that more than 90 per cent of those eligible for a pension boost are not expected to get what they are entitled to. The government has reduced the amount set aside to settle any arrears from £1 billion to £29.8 million. It has so far paid £104 million to correct the records of 12,379 pensioners.

Steve Webb, a former pensions minister and now a partner at the pensions consultancy LCP, said: “The figures are a shocking reduction in the amount of state pension arrears that the DWP now expects to pay out to mothers with errors on their national insurance record.

“It has been a dismal failure and this was entirely predictable given its reliance on a complicated online claims process. Although there will still be some publicity, the latest figures are an admission that the government does not expect these efforts to have much impact.

“It has all but given up on these mothers and this is totally unacceptable. It is time for a fresh campaign of direct mail to the women potentially affected, this time making it much easier for women to apply, supported by a fresh publicity blitz.”

The DWP said that correcting Home Responsibilities Protection claims was “inherently challenging” and said that the low numbers claiming arrears was down to some believing that the HMRC letters were a scam. It said that others struggled to apply online and did not understand the relevance of the problem.