Marvin OnumonuDepartment for Work & Pensions (DWP) figures showed one in 10 Pension Credit claimants missed out on their full entitlement in the financial year ending 2025.
Around £100m went unclaimed, up from £80m the previous year.
The proportion of claims with unfulfilled eligibility rose from eight in 100 in 2024 to 10 in 100 in 2025.
Data showed that there are about 1.4 million Pension Credit claimants, meaning around 140,000 households missed out on an average of £700 each.
The department said most underpayments happened when claimants failed to provide accurate or up-to-date information.
Common reasons included a reduction in financial assets, a non-dependant moving out, or a fall in income from private pensions.
Stephen Lowe, group communications director at Just Group, said: “About 10% of claimants did not get their full entitlement in 2024-25 compared to 8% the previous years.
“The amount being underclaimed was also higher at £100m compared to £80m previously.
“There are about 1.4 million claimants overall, suggesting 140,000 households missed out on an average of about £700, which is a significant sum for those struggling on low incomes.”
Lowe added: “It’s important to understand what changes in circumstances can impact the amount of benefit being paid because the system relies on accurate information.”
He also pointed out that a bigger issue is people not claiming at all.
Only 65% of those eligible received Pension Credit in 2022 to 2023, with about 760,000 households missing out on an average of £1,900 each, or £1.5bn in total.
Lowe advised claimants to report changes in circumstances quickly and to review the information they have given.
He said: “You could be eligible for more, but you also must guard against accidentally overclaiming and then having to repay the money later which can cause serious hardship.”
