The Department is aware of a number of cases where individuals have been underpaid State Pension. We are checking for further cases and any that are found will be looked at in line with the relevant legislation and any arrears payments backdated to the point they became eligible. Those married women who are already getting a State Pension based on their own National Insurance contributions must make a separate claim for the Category BL top up if their husband reached State Pension age after them and before 17 March 2008. The top up payments can, in accordance with legislation, be backdated for a maximum of 12 months before the date the claim is made. Any individual who believes they are being underpaid State Pension should contact the Department on the Freephone number 0800 731 0469. Further details on how to do this through the Pension Service are available on the gov.uk website.