How to Use the UK National Insurance Calculator
The UK National Insurance Calculator computes employee Class 1 NI, employer Class 1 NI, self-employed Class 4 NI, and Class 2 NI contributions for 2025/26. It handles all thresholds and rates accurately, including the recent changes that took effect in April 2025.
Enter your employment income or self-employment profits and select your employment type. The calculator shows the breakdown of contributions by rate band, your NI total, your employer's NI liability, and the effect of NI on your overall take-home pay.
A significant 2025/26 change: employer NI (Class 1 secondary) increased from 13.8% to 15% from April 2025, and the Secondary Threshold fell from £9,100 to £5,000. This substantially increased employer costs, with knock-on effects on hiring decisions, pay rises, and gig economy workers reclassified as employees.
📊 Worked Example
£40,000 salary, employee and employer NI (2025/26):
- Employee NI (Class 1): £2,184 (8% on £27,430)
- Employer NI (Class 1): £5,250 (15% on £35,000)
- Total NI cost to employer: £5,250 (paid by employer)
- True employer cost of hiring: £45,250
Common Use Cases
- ✅ Calculating your National Insurance deduction from your payslip
- ✅ Understanding employer NI costs for budgeting staff costs
- ✅ Calculating self-employed Class 4 NI on business profits
- ✅ Understanding how NI interacts with income tax for total tax burden
- ✅ Planning salary sacrifice to reduce both income tax and NI
- ✅ Calculating NI for payroll purposes across different salary levels
Frequently Asked Questions
What are the employee NI rates for 2025/26?
Employees pay 8% Class 1 NI on earnings between £12,570 and £50,270 per year (£242–£967/week). Above £50,270, the rate drops to 2%. Below £12,570 (Primary Threshold), no employee NI is due, but NI credits are earned above the Lower Earnings Limit (£6,396). These rates apply from April 2025.
What changed with employer NI in April 2025?
The employer NI rate increased from 13.8% to 15%, and the Secondary Threshold (the earnings above which employers pay NI) reduced from £9,100 to £5,000 per year. This means employers pay NI on more of each employee's salary and at a higher rate — a significant increase in employment costs. The Employment Allowance increased to £10,500 to partially offset this for small businesses.
How does National Insurance affect State Pension?
You need 35 qualifying years of National Insurance contributions to receive the full New State Pension (£11,502/year in 2025/26). You need 10 qualifying years for any State Pension. You can check your NI record and State Pension forecast on the HMRC website. Gaps can sometimes be filled voluntarily.
Can I reduce my NI through salary sacrifice?
Yes. Salary sacrifice for pension contributions reduces both the salary subject to employee NI and, crucially, the salary subject to employer NI. This is why many employers encourage pension salary sacrifice — they also save on their employer NI bill. The saving can be used to increase the employer's pension contribution.
How is NI different from income tax?
Income tax funds general government spending. National Insurance funds (in theory) the State Pension, NHS, and some benefits. Income tax applies from the personal allowance (£12,570); NI applies from the Primary Threshold (also £12,570 from 2022). The key difference is that NI is not charged on pension income or investment income — only on earnings and self-employment profits.