How the primary threshold works
Primary means the employee's share; secondary means the employer's. Each pay period is tested separately: a monthly-paid employee's NI is worked out on that month's pay against £1,048, not on the year's total. That is why NI, unlike income tax, is not cumulative.
The yearly PT, £12,570, matches the standard personal allowance for income tax in 2026/27, so someone on a 1257L code starts paying both at roughly the same point. The rates above it depend on the category letter. HMRC's table gives 8% then 2% for A, F, H, M, N and V; 1.85% then 2% for the reduced-rate letters B, E and I; 2% throughout for D, J, L and Z; and nothing for C, K and S.
Employee NI on two monthly salaries
| Monthly pay | 8% band | 2% band | Employee NI |
|---|---|---|---|
| £2,600 | £1,552 × 8% = £124.16 | £0 | £124.16 |
| £5,000 | £3,141 × 8% = £251.28 | £811 × 2% = £16.22 | £267.50 |
On £2,600 only the slice above £1,048 is charged. On £5,000 the 8% stops at the £4,189 upper earnings limit, and the remaining £811 is charged at 2%. A month of £1,000 would show no employee NI at all.
The PT behind the NI line on a payslip
Payslips show the result, not the threshold: one line called National Insurance or NI with the period amount and often a year-to-date figure. To check it, subtract the PT for the pay period (£242 weekly, £1,048 monthly) from gross pay for NI and apply the rate for the letter printed on the payslip. A pension contribution made through salary sacrifice lowers the pay that NI is measured on, because the cash pay itself is lower.
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Related terms
Questions
What is the primary threshold for 2026/27?
£242 a week, £1,048 a month or £12,570 a year, from 6 April 2026 to 5 April 2027. Employees pay Class 1 National Insurance on earnings above it.
Is the primary threshold the same as the personal allowance?
In 2026/27 the yearly figures match at £12,570, but they are different things. The personal allowance is for income tax and works across the year. The primary threshold is for National Insurance and is applied to each pay period on its own.
Why did I pay NI in one month but not another?
Because NI is tested pay period by pay period. A month with overtime or a bonus can pass £1,048 and trigger NI, while a quieter month below it shows none, even if the yearly total stays under £12,570.
Sources
- HMRC: Rates and thresholds for employers 2026 to 2027 (read 8 October 2026)
- GOV.UK: National Insurance (read 8 October 2026)
Figures are for the 2026/27 tax year unless the text says otherwise. This page explains a payroll term; it is general information, not tax or legal advice.