Essentially, if someone reaches state pension age in June 2022, they will have to continue paying class four contributions until April 5, 2023. 

Even then, their final class four bill and income tax will be paid on January 31, 2024. 

Generally, people who have reached state pension age will only need to pay income tax if their taxable income exceeds their tax-free allowances. 

Employees who continue working past state pension age can show their employer proof of their age to ensure they stop paying NI contributions.