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UK National Insurance Explained: Rates, Thresholds & What You Pay in 2024/25

🕑 6 min read  ·  FinCalcHub Editorial

National Insurance (NI) is a UK tax on earnings that funds the NHS, State Pension, and certain benefits. It's deducted from your payslip alongside income tax, but it works differently — with its own thresholds, rates, and qualifying year rules.

2024/25 Class 1 Employee NI Rates

Employer NI (Class 1 Secondary)

Employer NI is not visible on your payslip but is a real labour cost. For a £40,000 employee, the employer pays roughly £4,262 in NI on top of salary. Total employment cost: ~£44,262.

Worked Example: £35,000 Salary

1. Earnings above lower threshold: £35,000 − £12,570 = £22,430
2. NI at 8%: £22,430 × 8% = £1,794/year (£149.50/month)

How NI Builds State Pension Entitlement

Each tax year you pay sufficient NI (or earn NI credits) counts as a qualifying year toward your State Pension. You need 35 qualifying years for the full new State Pension (£221.20/week in 2024/25). Each qualifying year is worth approximately £6.32/week (£329/year) in pension.

NI for Self-Employed (Class 2 & 4)

• Class 2: Abolished from April 2024 for most self-employed
• Class 4: 6% on profits £12,570–£50,270; 2% above £50,270
• Self-employed can still obtain NI qualifying years via Class 4 or voluntary Class 3 contributions

Voluntary Class 3 NI Contributions

If you have NI gaps (years abroad, career breaks, low income years), you can buy qualifying years at approximately £824 each. Given the State Pension gain of ~£329/year for life, payback is 2.5 years — one of the best guaranteed returns available to UK residents.

NI and Your Personal Allowance

NI and income tax use different thresholds. Income tax starts at £12,570 (Personal Allowance). NI also starts at £12,570 (Lower Profits Limit for employees). They're aligned in 2024/25, making payslip calculations more intuitive — but this wasn't always the case.