The single letter on the National Insurance line of your payslip is your NI category. It tells payroll which set of rates to apply, under the Social Security (Contributions) Regulations 2001. Most employees are category A. The letter usually reflects your age or your State Pension age status, not your job title.
Which category letter applies to whom?
| Letter | Who it applies to |
|---|---|
| A | Most employees, standard rate |
| B | Married women or widows with a valid reduced-rate election |
| C | Employees over State Pension age (no employee NI) |
| H | Apprentices under 25 |
| M | Employees under 21 |
| V | Qualifying veterans in their first year of civilian employment |
| J / Z | Deferred NI for those who already pay the maximum in another job (Z if under 21) |
| X | No NI liability, for example earnings below the threshold |
How does the letter change what I pay?
The letter sets the rate, not just a label. On category A you pay 8% on earnings between the Primary Threshold (£12,570 a year) and the Upper Earnings Limit (£50,270), then 2% above. Under-21s (M) and apprentices under 25 (H) pay the same employee rates, but the employer pays 0% up to £50,270, which is why employers track these letters. Our guide to the NI thresholds sets out the bands.
What if my category letter is wrong?
A wrong letter means you overpay or underpay National Insurance, so it is worth checking against your age and circumstances. Reaching State Pension age should move you to category C, after which employee NI stops. If the letter does not fit, ask payroll to correct it and reclaim or repay any difference. Freeport and Investment Zone roles use separate letters, including F, I, S and L.
Primary sources
- National Insurance rates and categories — gov.uk — The category letters and the employee and employer rates for each
- CA38: National Insurance contributions tables — gov.uk — HMRC tables setting the rate for each category letter
- Reduced rate National Insurance for married women — gov.uk — The category B reduced-rate election
- The Social Security (Contributions) Regulations 2001 — legislation.gov.uk — SI 2001/1004 — the statutory basis for NI categories and rates
Editorial process: how we source and review UK tax content.