National Insurance Category Letters Explained, With Worked Examples (2026/27)
Your payslip's NI category letter (A, B, C, H, M, X and others) determines how much National Insurance you and your employer actually pay. What each letter means in 2026/27.
Quick answer
The single letter next to your National Insurance number on a payslip determines the actual rates applied to your pay โ and it isn't always "A", the standard category. Apprentices, under-21s, over-State-Pension-age workers and a few legacy categories all follow different rules, which is worth understanding if your payslip's NI deduction looks different from what a standard calculation would suggest.
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National Insurance calculatorThe common categories
- A โ the default for most employees: 8% employee NI between the primary threshold (ยฃ12,570) and upper earnings limit (ยฃ50,270), 2% above; standard employer NI (15% above the ยฃ5,000 secondary threshold) also applies.
- C โ employees over State Pension age. No employee NI is deducted at all (since NI is no longer due once past State Pension age), though the employer still generally pays employer NI on their earnings.
- H โ apprentices under 25 on a recognised apprenticeship. Employer NI is reduced to zero up to the upper secondary threshold for apprentices, an incentive for employers to take on and properly register apprentices.
- M โ employees under 21. Similarly, employer NI is reduced to zero up to the upper secondary threshold, without changing the employee's own NI liability, which still follows the standard rates.
- X โ no NI liability arises, commonly because earnings are below the lower earnings limit.
Legacy categories
Category B applies to a small, closed group โ some married women and widows who registered a historic reduced-rate NI election decades ago (no longer available to new claimants), paying a reduced employee rate but forfeiting some contributory benefit entitlement built on their own record.
uk-national-insurance-contributions-guideWhy the category matters to you
If your payslip shows a category other than A and you're not sure why, it's worth checking โ an apprentice or under-21 correctly coded H or M won't personally see a different employee deduction, but it materially affects what their employer pays, which is sometimes relevant context in pay negotiations or when checking your employer has registered your employment correctly. An employee incorrectly left on category A rather than C after reaching State Pension age would be having National Insurance wrongly deducted and should query it with payroll immediately.
Bottom line
Check your own payslip's NI category letter rather than assuming it's the default "A" โ apprentices, under-21s and over-State-Pension-age employees especially should confirm they're on the category that actually applies to them.
Sources
- GOV.UK: National Insurance categories
- GOV.UK: Employer National Insurance rates
Frequently asked questions
What does NI category letter A mean?
Category A is the standard letter for most employees, applying the normal Class 1 employee National Insurance rates โ 8% on earnings between the primary threshold and upper earnings limit, and 2% above that โ with standard employer National Insurance also due.
What is category H for?
Category H applies to apprentices under 25 on an approved apprenticeship, who benefit from a reduced or zero employer National Insurance liability up to the upper secondary threshold, encouraging employers to take on apprentices.
What does category M mean on a payslip?
Category M applies to employees under 21, who similarly benefit from reduced or zero employer National Insurance up to the upper secondary threshold, without changing the employee's own National Insurance liability.
What is category X, and why would my employer use it?
Category X is used where no National Insurance liability arises at all โ for example, where earnings are below the lower earnings limit, or in certain other specific no-liability circumstances defined by HMRC.
Why might someone be on category C or B rather than A?
Category C applies to employees over State Pension age, who don't pay employee National Insurance (though employer NI can still apply). Category B applies to certain married women or widows who retain the historic reduced-rate election, a legacy category not available to new claimants but still used by some long-standing employees who registered it decades ago.
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