Is it worth buying missing NI years? The break-even maths.
Class 3 voluntary NI contributions let you buy back missing years in your NI record. The cost is fixed; the benefit is a higher state pension for the rest of your life. For most people the return is exceptional. But not for everyone.
- ▸One missing NI year costs £824.20 to buy back via Class 3 voluntary contributions (2024/25 rate). It adds approximately £6.32/week (£329/yr) to your state pension — a break-even of about 2.5 years.
- ▸If you live to average life expectancy you will collect roughly 20 years of state pension. A single bought year returns over £6,500 at today's rates — before triple lock increases.
- ▸The 2024/25 deadline for plugging gaps back to 2006 has been extended by HMRC before — but gaps do eventually close. Check the current deadline and act before the window shuts.
- ▸Buying years is less compelling if you already have 35 qualifying years, if you are likely to get credits before retirement anyway, or if you are in very poor health.
- ▸Use our NI gap top-up calculator to model the exact numbers for your own situation.
The cost of a missing NI year
Class 3 voluntary NI contributions are the standard mechanism for plugging gaps. For 2024/25 the rate is £17.45 per week — or £824.20 for a full year (52 × £17.45, with a small rounding adjustment that HMRC applies in practice).
Historical gap years can usually be filled at the rate that applied in that year, which is often cheaper than the current rate. However, HMRC simplifies this and you should check the actual cost for each specific gap year via your personal NI record on gov.uk or by calling HMRC.
The rate rises modestly each year in line with policy, so gaps bought now will generally be cheaper than the same gaps bought in future years.
The return: extra state pension for life
Every qualifying year you add moves your state pension entitlement by one thirty-fifth of the full amount.
The full new state pension in 2025/26 is £221.20 per week. One thirty-fifth of that is £6.32 per week, or approximately £329 per year.
That £329 per year is paid for the rest of your life from state pension age. It is also uprated annually by the triple lock — the higher of earnings growth, CPI inflation, or 2.5% — so the real value of that extra income tends to grow over time.
The break-even calculation
Divide the cost by the annual gain:
£824.20 ÷ £329.00 = approximately 2.5 years
After two and a half years of drawing the higher state pension, you have recovered the cost in nominal terms. Everything after that is pure gain.
To put it another way: if you reach state pension age and live for another 20 years (roughly average UK life expectancy from age 66), that one bought year returns:
20 × £329 = £6,580 in today's money — before triple lock uprating.
The after-tax picture is also worth considering. State pension counts as taxable income, but many people are below the personal allowance in retirement, meaning the extra state pension is received tax-free. Even for basic-rate taxpayers the after-tax return (roughly £263/yr) still breaks even in about 3.1 years.
No savings account, ISA, or annuity comes close to this rate of return for people who are in reasonable health.
The deadline for historical gap years
HMRC periodically extends the window for topping up historical gaps. As of 2024/25 you could fill gaps going back to 2006/07 — a span of nearly 20 years. This extended window has been renewed several times, but it will not remain open indefinitely.
Once a gap year falls outside the fillable window, it is permanently lost. The standard rule is that gaps older than six years cannot be filled — the extended window is an exception, not the norm.
Check the current deadline on gov.uk before assuming you have plenty of time. If you have gaps from the 2006–2016 period in particular, those are the ones most at risk of closing.
Use the state pension forecast calculator to see how your current record translates into a weekly amount, then use our NI gap top-up calculator to model the return on each gap year.
When it is NOT worth it
Buying missing NI years is not universally the right move. There are four situations where it may not make sense:
1. You already have 35 qualifying years. Additional years beyond 35 do not increase your state pension. If your record already shows 35 or more qualifying years — even with some gaps — filling those gaps is pointless.
2. You will accumulate enough years anyway. If you are in your 40s with 25 qualifying years and still working, you will likely reach 35 years naturally before retirement. Paying for years you will earn for free is wasteful.
3. You are in poor health. The break-even assumes you survive to collect. If you have serious health conditions that reduce life expectancy substantially, the calculation shifts. At 2.5 years to break even the margin is still comfortable for most people, but if you are unlikely to draw the pension for more than a year or two it is harder to justify.
4. The year is already credited or will be credited. Some people assume they have a gap when actually a credit is pending — for example, if Child Benefit NI credits have not yet been applied to the record. Check the actual gap on gov.uk before paying to fill it.
- ▸Class 3 voluntary NI contributions cost £17.45/week (£824.20/year) for 2024/25, allowing gaps in your NI record to be filled. [gov.uk]
- ▸Each additional qualifying year adds 1/35th of the full new state pension — approximately £6.32/week (£329/yr) at 2025/26 rates. [gov.uk]
- ▸As of 2024/25, HMRC extended the window to fill gaps going back to 2006/07. The standard fillable window is only the past six years. [gov.uk]
- ▸The full new state pension is £221.20/week (£11,502/yr) for 2025/26, uprated annually by the triple lock. [gov.uk]