The main National Insurance classes
Class 1 contributions apply to employment earnings. Employers pay separate secondary Class 1 contributions, while most self-employed calculations use Class 4 contributions based on profit. Voluntary Class 3 contributions can sometimes fill gaps in a National Insurance record.
Why employer National Insurance matters
Employer National Insurance is paid on top of salary and does not appear as a deduction from employee take-home pay. It is still part of the employer's total cost of employing someone.
National Insurance and the State Pension
National Insurance contributions and credits can build qualifying years for the State Pension. The amount paid in a year is not the same as the pension amount earned, and gaps may need separate checking through a personal tax account.