Campaign to ensure mothers receive state pension
Mothers are being urged to check whether they are being underpaid their state pension after errors emerged with National Insurance records.
Since 1978, the system has included credits for parents who took time out of employment to bring up children.
But the government has acknowledged that details were absent in an unknown number of cases.
Pension consultants LCP have launched a tool to allow people to check they are not missing out.
As reported in July, the Department for Work and Pensions (DWP) admitted to an error in which credits for time at home with children - previously known as Home Responsibilities Protection (HRP) - may be missing from people's National Insurance records and therefore affect their state pension.
Sir Steve Webb, a former pensions minister who is now a partner at LCP, said: "Yet again, this error overwhelmingly affects women, and undoubtedly means that many thousands have been underpaid for years.
"Rather than wait for the government to fix the problem, I would encourage anyone who has received child benefit since 1978/79 to check that the relevant credits are on their NI record. If not, this can be fixed by filling in a form, and the result could well be a higher pension and a worthwhile lump sum."
Sir Steve told BBC Radio 4's Woman's Hour that the problem had emerged more than a decade ago, and had been thought to have been fixed. However, he said fresh enquiries had unearthed new cases, some of which could lead to thousands of pounds paid in backdated pension.
In one case seen recently by LCP, Lorraine Wainwright, 68, from Gloucestershire, was given a lump sum of around £1,500 and her regular state pension will now be increased by more than £20 per week, after Sir Steve took up her case.
Mrs Wainwright said: "If I had not checked my own record carefully, it is quite possible I would still be getting the wrong rate of pension. I welcome this new campaign, which could help thousands of mothers to get their dues."
HM Revenue and Customs (HMRC) said Mrs Wainwright first contacted it in June 2020 enquiring about HRP. The tax agency said it sent her a form, which it received back, but could not reach her by phone to get further information, so wrote to her again. It then received an official application for HRP from Mrs Wainwright in March 2022 and has since written to her informing her of her award.
Department for Work and Pensions said it was working with HMRC to identify those affected by the historical issue.
LCP advises large company pension schemes and is not making money from the campaign. No payment is needed for people to check their entitlement.
roblem is second in scale to a scandal which has seen many thousands of pensioners - mostly women - underpaid their state pension. MPs branded the issue as "shameful".
In that case, the latest estimate from the DWP suggested 237,000 state pensioners were paid less than their entitlement, with a total of nearly £1.5bn underpaid.
ue dates back to 1985 and relates to the "old" state pension system. 
Married women who had a small pension of their own could claim a 60% basic state pension based on their husband's record of contributions. An error at the DWP meant they were not automatically given this money.