The Department for Work and Pensions (DWP) has been working over the past three years to rectify historic state pension underpayments.

The department is on track to resolve the issue by year's end, having made thousands of back payments to those unjustly underpaid since the error was discovered in 2021.

So far, many of the 119,050 affected pensioners have received average payments between £2,202 and £11,905 depending on which category they fall into.

The main groups impacted by the system error are those who reached state pension age before April 6, 2016:

Much of the DWP's work over the past few years has involved identifying those affected and calculating their due back payments.

This task was complicated by the fact that some people received overpayments of other benefits like Pension Credit due to the underpayments, therefore they weren't actually being underpaid overall.

So far, all of the impacted married women and pensioners over 80 should have been reimbursed, with the last few individuals in the widow category set to receive their dues before the start of 2025.

The system error was exposed to the DWP in 2021 through a Legal Entitlements and Administrative Practice exercise, known as a LEAP exercise, and became the largest underpayment correction in the department's history, totalling £736 million owed.

However, the department is also addressing other state pension underpayments. The Home Responsibilities Protection affected some people on the old state pension system as it didn't properly record this protection on their National Insurance records.

Approximately 5,000 affected people have been identified this year with an average payout of £7,859. Those affected by this, primarily women who might have been entitled to HRP between 1978 and 2010, should have received a letter from HMRC.

Lastly, another group potentially affected by other state pension underpayments are those claiming Universal Credit. Due to a system issue between 2017-2018 and 2022-2023, individuals who were due to get National Insurance credits through their benefit may not see them properly translated to their National Insurance record.

This could impact how much state pension they receive. The quickest way to check for underpayments is to contact the Pension Service on 0800 731 0469.