This is what the latest National Insurance Fund Annual Report to 31 March 2025, dated 27 November 2025 says:
Underpayment of State Pension – Home Responsibilities Protection (HRP)
[An issue causing] underpayment of State Pension was identified in 2021 to 2022 in connection with HRP. DWP’s annual fraud and error exercise identified administrative discrepancies in the recording of HRP on some customers’ National Insurance records, resulting in State Pension errors. In response, the government launched a dedicated correction exercise involving both HMRC and DWP.
Despite extensive communications, a low number of people applied to correct their missing HRP. Following significant operational effort, DWP and HMRC jointly decided to conclude the exercise in April 2025, after which any remaining cases will be managed through business-as-usual processes.
Due to the low response rate, HMRC’s Internal Audit team completed an assurance review and made 5 recommendations. 2 have been completed and the remaining 3 are expected to be completed by March 2026.
Between January 2024 and March 2025, 21,878 claimant records were reviewed by DWP and 12,379 underpayments identified, with total arrears paid of approximately £104 million.
DWP has recognised a provision of £30 million in their 2024 to 2025 Annual Report & Account, though the final value remains subject to change as outstanding cases are resolved.
In other words, there could still be £30 million in underpaid pension.