Formula
Apply the employee Class 1 rates to the pay falling within each threshold band for the selected pay period.
UK payroll estimate
UK National Insurance Calculator
Estimate employee Class 1 National Insurance from weekly or monthly pay. Other category letters, directors and special cases can differ.
Estimated NI
Enter values to calculate Calculation basis date: 17 May 2026. Category A employee National Insurance estimate.Calculation Basis and Official Sources
Calculation basis date: 17 May 2026. Uses GOV.UK National Insurance information for employee Class 1 category A assumptions.
For payroll processing, check HMRC guidance, payroll software, your employer or an accountant.
Formula and Interpretation
How to read it
This is a payroll estimate for category A. Actual NI can differ for other letters, directors, refunds or payroll timing.
This calculator and its examples are for general information and rough estimation only. They are not legal, tax, accounting, payroll, lending, mortgage, investment, insurance, medical or other professional advice.
Rates, bands, thresholds, deductions, credits, local rules, employer settings, lender terms, product rules and personal facts can change. We do not guarantee that the calculations are accurate, complete, current or suitable for your situation.
UK note: this page is not legal, tax, accounting, payroll, mortgage, benefits, insurance or financial advice. Check GOV.UK, HMRC, your employer, lender, solicitor, accountant or qualified adviser before acting.
Before You Rely on the Result
Practical examples
Enter monthly pay of GBP 3,500 to estimate employee NI for that month.
Switch to weekly if your payslip is weekly.
Use the PAYE salary calculator if you also need income tax and pension estimates.
What this includes
- Employee Class 1 NI estimate
- Weekly or monthly threshold selection
- Category A main/additional rates
What this does not include
- Employer NI and employment allowance
- Other category letters and directors' annual method
- Class 2, Class 3 or Class 4 contributions
When to check official sources
Use HMRC guidance and payroll software before running payroll or disputing deductions.