Employers use an employee’s National Insurance category letter when they run payroll to work out how much they both need to contribute.
Most employees have category letter A, which means that normal Employee and Employer Class 1 National Insurance Contributions (NICs) are payable. You should be able to see your category letter on your payslip.
This is what the other letters mean:
|B||Married women and widows who opted before April 1977 to pay reduced NICs|
|C||Employees over the State Pension age|
|J||Employees who can defer NI because they’re already paying enough in another job|
|H||Apprentice under 25|
|M||Employees under 21|
|Z||Employees under 21 who can defer NI because they’re already paying it in another job|
Category letter X is for employees who do not have to pay NICs, for example because they are under 16.
The current National Insurance rates and thresholds are set out in our Tax Rates and Allowances pages