Pensions 6 min read • March 2026

National Insurance gaps — should you fill them?

Your State Pension depends on your National Insurance record. Gaps in that record — years where you didn't pay enough NI — directly reduce what you'll receive. Voluntary contributions can fill those gaps, and for many people the maths is compelling. But it's not automatic.

How State Pension qualifying years work

You need 35 qualifying years for the full new State Pension (£11,502/year in 2025/26). Each qualifying year adds approximately £329/year to your State Pension. You need a minimum of 10 qualifying years to receive anything at all.

A qualifying year is one in which you paid (or were credited with) at least 52 weeks of NI contributions. Credits are given automatically for periods of unemployment, carer's allowance, and some other situations.

Who gets gaps?

Common causes of NI gaps include: self-employment with lower profits (below the Small Profits Threshold), periods of unemployment without claiming credits, studying or travelling abroad, caring for family without registering for carer's credits, and periods of low earnings below the lower earnings limit.

The cost to fill a gap

Voluntary Class 3 NI contributions cost approximately £824 per missing year (2025/26 rate). Each year filled adds roughly £329/year to your State Pension. The payback period is about 2.5 years — meaning if you live more than 2.5 years past State Pension age after filling the gap, it pays off financially.

⏰ Time-sensitive: extended backfill window

HMRC has allowed people to backfill NI gaps going back to 2006 (rather than the usual 6-year window). This extended window is open until April 2025 — after which only the standard 6-year lookback applies. If you have pre-2019 gaps, check urgently whether you can still fill them.

Class 2 vs Class 3 contributions

If you're self-employed, you may be eligible to pay the much cheaper Class 2 voluntary contributions (~£179/year vs £824 for Class 3) to fill gaps from self-employed years where your profits were too low to pay NI automatically. Worth checking specifically if you've had self-employed years with low income.

Before you pay — check three things

1. Check your actual NI record at gov.uk/check-state-pension. You can see your current qualifying years, any gaps, and a State Pension forecast. 2. Confirm the gap is genuinely a gap — some gaps are already covered by credits you weren't aware of. 3. Check whether you have enough future years to reach 35 without filling gaps — if you're 40 with 20 qualifying years and 25 working years remaining, you'll reach 35 without filling any gaps.

Use the to model your projected pension, the cost of filling gaps, and the payback period.