National Insurance Calculator UK 2026: Complete Guide to Class 1, 2 & 4 NI Contributions

Introduction

National Insurance is one of those deductions that quietly takes a significant chunk of your income, yet most people struggle to explain what it is or how it works. If you are employed, you see NI deducted from every payslip — typically 8% of your earnings between £12,570 and £50,270. If you are self-employed, you pay a combination of Class 2 and Class 4 contributions through your Self Assessment tax return.

The problem is that NI rules are different for employees and self-employed people, the thresholds change every year, and the rates have shifted significantly in recent budgets (the main employee rate dropped from 12% to 8% in 2024, and the Class 4 rate fell from 9% to 6%). Keeping track of what you actually owe — and planning to minimise it — requires an accurate, up-to-date calculator.

That is why we built the National Insurance Calculator UK. This tool gives you an instant, accurate breakdown of your NI contributions for the 2025–26 tax year, whether you are employed (Class 1) or self-employed (Class 2 and Class 4). It also shows your employer's NI contribution — a cost you should know about when negotiating your salary.

This guide walks you through every NI class, explains the formulas behind the calculator, and gives you real-world examples for the 2025–26 tax year.

How to Use This Calculator

The National Insurance Calculator UK is designed to be fast and flexible. Here is exactly how to use it:

Select Your Employment Type — Choose "Employed" for Class 1 NI or "Self-Employed" for Class 2 and Class 4 NI.
Enter Your Income — If employed, enter your gross annual salary. If self-employed, enter your annual profits after allowable expenses.
Read Your Results — The calculator instantly shows your NI contributions broken down by class, your effective NI rate, your monthly deduction, and your income after NI.

Pair this calculator with our Income Tax Calculator UK to see your complete tax picture, or Self Assessment Tax Calculator UK if you are self-employed and need your full tax bill.

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Select your employment type and enter your income to see your NI contributions in seconds.

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Complete National Insurance Formula Breakdown

Class 1 (Employee) NI — 2025–26 Rates

If you are employed, your employer deducts Class 1 NI from your salary through PAYE. The rates are:

0% on earnings up to £12,570 (Primary Threshold)
8% on earnings between £12,570 and £50,270 (Upper Earnings Limit)
2% on earnings above £50,270

Example: On a £45,000 salary:

Earnings between £12,570 and £45,000: £32,430 × 8% = £2,594
Class 1 NI: £2,594 per year (£216 per month)

Class 2 (Self-Employed) NI — 2025–26 Rates

If you are self-employed and your annual profits exceed £12,570, you pay a flat rate of £3.45 per week (£179.40 per year). This entitles you to certain state benefits including the State Pension, Maternity Allowance, and contributory Jobseeker's Allowance.

Class 4 (Self-Employed) NI — 2025–26 Rates

In addition to Class 2, self-employed people pay Class 4 NI as a percentage of their annual profits:

6% on profits between £12,570 and £50,270
2% on profits above £50,270

Example: On £40,000 self-employed profits:

Class 2: £3.45 × 52 = £179
Class 4: 6% of (£40,000 - £12,570) = 6% of £27,430 = £1,646
Total NI: £1,825 per year

Employer NI — 2025–26 Rates

Your employer pays 15% on your earnings above £9,100 per year (secondary threshold). For a £45,000 salary: (£45,000 − £9,100) × 15% = £5,385 in employer NI. This is a cost to your employer and part of your total compensation package.

Real-Life Examples

Scenario 1 — Employed, £35,000 Salary

On £35,000 as an employee: Class 1 NI = 8% of (£35,000 − £12,570) = 8% of £22,430 = £1,794 per year (~£150/month). Your employer pays an additional 15% of (£35,000 − £9,100) = £3,885 in employer NI.

Scenario 2 — Self-Employed, £40,000 Profits

Class 2 NI = £3.45 × 52 = £179. Class 4 NI = 6% of (£40,000 − £12,570) = £1,646. Total NI: £1,825. This is significantly less than an employee on the same income (£2,249) because self-employed people don't get the same contributory benefits.

Scenario 3 — Higher-Rate Earner, £85,000 Salary

NI at 8% on £37,700 (£50,270 − £12,570) = £3,016. NI at 2% on £34,730 (£85,000 − £50,270) = £695. Total Class 1 NI: £3,711 per year (~£309/month).

Key Things to Know About UK National Insurance in 2025–26

Class 1 rate cut: The main employee rate was cut from 12% to 8% in January 2024 and remains at 8% for 2025–26, saving the average earner roughly £450 per year.
Class 4 rate cut: The self-employed Class 4 rate was cut from 9% to 6% in April 2024 and remains at 6%, saving the average sole trader roughly £700 per year.
Employer NI increase: From April 2025, the employer NI rate increased from 13.8% to 15%, making it more expensive for businesses to hire employees.
NI and the State Pension: You need at least 35 qualifying years of NI contributions to receive the full State Pension. Missing years can be filled with voluntary contributions.
NI and benefits: NI contributions entitle you to certain state benefits including the State Pension, Maternity Allowance, Contribution-based Jobseeker's Allowance, and Employment and Support Allowance.

Tips to Minimise Your National Insurance

Optimise your salary structure: If you are a company director, consider taking a combination of salary (up to the NI threshold) and dividends to minimise both employee and employer NI.
Use salary sacrifice schemes: Pension contributions through salary sacrifice reduce your earnings for NI purposes, saving both employee and employer NI. A £5,000 pension sacrifice on a £50,000 salary saves you £400 in employee NI and your employer £750 in employer NI.
Claim all allowable expenses: If self-employed, make sure you claim every allowable expense — they reduce your profits and therefore your Class 4 NI bill.
Time your profits: If you are close to the £50,270 upper profits limit (£100,000 for the personal allowance taper), consider deferring income or bringing forward expenses to stay in the lower NI band.

Frequently Asked Questions

What is the current National Insurance rate in the UK for 2025–26?

For employees (Class 1): 8% on earnings between £12,570 and £50,270, and 2% above £50,270. For self-employed (Class 4): 6% on profits between £12,570 and £50,270, and 2% above £50,270. Plus Class 2 at £3.45/week.

Do I pay National Insurance if I'm self-employed?

Yes. Self-employed people pay Class 2 NI (£3.45 per week) and Class 4 NI (6% on profits between £12,570 and £50,270, 2% above) on their annual profits. You'll report and pay these through your Self Assessment tax return.

What's the difference between Class 1, Class 2, and Class 4 NI?

Class 1 is paid by employees and deducted through PAYE. Class 2 is a flat weekly amount paid by self-employed people. Class 4 is a percentage of profits paid by self-employed people. Each class provides different benefits and entitlements.

How many years of NI contributions do I need for the full State Pension?

You need 35 qualifying years of NI contributions or credits to receive the full State Pension. If you have fewer than 35 years, your pension will be proportionally reduced. You need at least 10 qualifying years to get any State Pension at all.

What is the employer National Insurance rate in 2025–26?

Employers pay 15% National Insurance on employee earnings above £9,100 per year (secondary threshold). This is a cost to the employer and part of the total employment package.

Conclusion

Understanding your National Insurance contributions is essential for accurate financial planning. Our National Insurance Calculator UK gives you an instant, accurate breakdown of your NI for the 2025–26 tax year.

Your next steps:

Open the National Insurance Calculator UK and run your numbers.
Check your complete tax picture with our Income Tax Calculator UK.
If self-employed, estimate your full tax bill with Self Assessment Tax Calculator UK.