From 6 April 2026, the increase will be phased in over the course of two years, meaning that people born between 6 April 1960 and 5 March 1961 will reach their state pension age at 66 years and a specified number of months.

HMRC is warning employers to check which staff fall into the category and can use the state pension age calculator to find the date when an individual will reach state pension age.

Once an employee reaches state pension age they no longer have to pay national insurance contributions (NICs), but employer’s Class 1 national insurance is still payable.

Employers with employees born between 6 April 1960 and 5 March 1961 should check the date at which individuals reach state pension age so they can update their national insurance rates and categories and issue the category letters at the correct time, which is the first payment date after the employee has reached state pension age.