Thousands of women could miss out on a cash payment after a government error.

Sir Steve Webb, the pensions minister between 2010 and 2015, has said that an HMRC campaign to track down over 180,000 women is set to fail. The women reportedly missed out on national insurance credits for time raising children.

An estimated 187,000 pensioners (43,000 of whom are dead) were underpaid their state pension due to gaps in their national insurance records, according to the Department of Work and Pensions. They estimated that just over £1billion would have to be paid out in arrears.

HMRC issued more than 250,000 letters to women over pension age with no Home Responsibilities Protection (a scheme to help protect parents and carer state pension), encouraging them to submit a claim.

A Freedom of Information request by Mr Webb revealed that the letters only offer online-based cash claiming, which leaves out those pensioners who don’t use the internet. Not referenced by the letters is the simple paper claim form (CF411) which can be used instead of the online form.

Mr Webb told the i paper: “Whilst I understand the desire of government departments to cut costs, it is completely inappropriate to write letters to hundreds of thousands of pensioners which suggest that the only way to apply is online.

“At the very least, the letter should give recipients a phone number to call or include a paper form for those who are not online. I am concerned in particular for older pensioners who may not have friends or family to help them.”

He said those who have been underpaid have typically missed out on thousands of pounds, and “deserve to have this put right”.

Age UK suggests that 29 percent of people aged 75 and over never use the internet, which suggests that many may not be able to act upon the letter’s instructions.

Sir Steve is now calling on HMRC to review how it communicates with older pensioners to make paper claim forms more readily available.

He added: “Unless HMRC addresses this issue it is highly likely that tens of thousands of older pensioners may continue to miss out on money which is rightfully theirs.”