Around 210,000 people across Britain could be owed thousands in state pension arrears because of historic HM Revenue and Customs (HMRC) errors involving the Home Responsibilities Protection scheme.
The scheme, which operated between 1978 and 2010, was designed to protect the state pension entitlement of people who reduced their working hours or stopped working to raise children or care for disabled or chronically ill relatives.
HMRC figures show the average underpayment is £8,377 per person.
The issue stems from decades-old administrative errors, with National Insurance records not always being correctly linked to Child Benefit or Family Allowance claims.
The total amount owed in state pension underpayments has now exceeded £800million.
Because National Insurance numbers were often missing from Child Benefit applications submitted before 2000, HMRC and the Department for Work and Pensions (DWP) have been unable to identify every affected individual.
The Government disclosed the issue in the Department for Work and Pensions Annual Report and Accounts for 2022-23.
It began writing to potentially affected pensioners in September 2023, sending more than 370,000 letters.
That letter-writing campaign has now ended.
Personal finance expert Martin Lewis warned on X that pensioners must now check whether they could be affected.
He wrote: “The Govt was contacting people, but isn’t any longer. Thus the onus is on YOU to proactively check.”
The responsibility has now shifted to individuals to check whether errors in their National Insurance record may have reduced their state pension entitlement.
One woman, named Cilla, contacted Mr Lewis’s team after receiving a substantial repayment.
She wrote: “I’ve just received 15yrs’ back pay from HMRC of £31,674 for underpayment of my pension.”
He added that some people could be owed sums running into the tens of thousands of pounds.
Pension reclaim firm AskRose said it is currently working with around 100,000 women who may be entitled to compensation.
The company stressed that having children during the relevant period does not automatically mean someone qualifies, as the protection applied only to people who reduced their working lives to provide care.
AskRose said dozens of its clients have died after submitting claims before receiving the money they were owed.
The firm’s director, Elaine Walker, said: “In the time it has taken to open this process up, too many of our clients have sadly passed away before being able to claim the money they were owed.
“They were left, in some cases, for more than 15 years without a fair pension and were then unable to even enjoy getting their recompense.”
HMRC’s letter campaign, which began in 2023, achieved a response rate of eight per cent.
Advisers have also warned that additional claimants have died while waiting for their cases to be resolved.
To qualify for a review, people must have been receiving their state pension for at least one year.
With the state pension age currently set at 66, this means applicants must be at least 67 years old.
People whose National Insurance contributions were fully and correctly recorded throughout their working lives will not qualify.
The Home Responsibilities Protection scheme applied only to people who reduced their working hours or stopped working to care for others.
Potential claimants may have received Child Benefit for a child under the age of 16, been the primary carer while their partner claimed Child Benefit, received Income Support as a carer, or looked after someone who was sick or disabled and claiming certain benefits.
A free self-identification tool is available on GOV.UK, allowing people to check whether they may be eligible and submit an application.
Once an application has been processed by HMRC and the DWP, cases typically take between four and six months to resolve.
