How-to
Overriding NI category for an employee
Employee detail > Employment > NI category. Default A. Override for under-21 (M), apprentice under 25 (H), director (C + is_director flag), veteran (V), or deferment (J/Z).
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Quick reference
| Override | When |
|---|---|
| M | Employee is under 21 — employer NI saving (0% to UEL) |
| H | Apprentice under 25 — employer NI saving |
| C | Employee over State Pension age, OR director paid only above the PT |
| V | Veteran in first year of civilian employment — employer NI saving |
| J | Employee has deferred NI elsewhere |
| Z | Under 21 with deferred NI elsewhere (M + J combined) |
| B | Married woman / widow with pre-1977 reduced-rate election (rare legacy) |
Default is A for everyone else.
To set
- Employee detail > Employment tab.
- Scroll to NI category.
- Pick from dropdown.
- Save.
Takes effect from the next pay run.
Director-specific: is_director flag
For directors, also toggle Is director on the Employment tab. This switches the NI calculation from periodic (per-period) to annual cumulative — useful when directors take variable pay (e.g. salary + bonuses) and you don't want NI smoothing to over-deduct early in the year.
Director method: calculates NI as if the employee had earned £X cumulative across the tax year, then subtracts NI already paid. Result: small period NI early in the year, larger NI later if they cross a band.
When to switch back to A
- Employee turns 21 — switch from M to A on or after their 21st birthday (manual)
- Apprentice turns 25 or completes apprenticeship — switch from H to A
- Veteran completes first year of civilian employment — switch from V to A
The system doesn't auto-switch — it's your responsibility to update on the right date.
Compliance
If you override incorrectly, HMRC catches the underpayment via RTI matching. Use the NI categories reference FAQ for guidance.