Cost and payback of buying NI years.
Total cost
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Extra pension per year
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Payback period
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Your breakdown
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Why a missing year is worth filling
The new State Pension is built from qualifying years on your National Insurance record. You generally need 35 full years to receive the maximum, and at least 10 to get anything at all. Years go missing for ordinary reasons: time spent abroad, low-paid or part-time work below the NI threshold, gaps for caring or study where you did not claim the right credits. Voluntary Class 3 contributions let you buy those gaps back, and because the extra pension is paid for the rest of your life, filling a cheap gap is often one of the highest-return things a saver can do with a few hundred pounds.
This calculator answers the practical question directly: what does it cost to buy the years you are missing, how much extra annual pension does that buy, and how quickly does the spending pay for itself. It is aimed at anyone within a decade or so of State Pension age who has checked their forecast and found they are short, though younger people with obvious permanent gaps can use it too.
What one Class 3 year buys
A single full Class 3 year for 2025/26 costs £907.40. Each qualifying year you add is worth roughly one thirty-fifth of the full new State Pension, which the tool models at £328.64 a year of extra pension. Set those two numbers side by side and the appeal is obvious: you pay £907.40 once and receive about £328.64 every year for as long as you live, so the contribution pays for itself in under three years of retirement and everything after that is profit. Few guaranteed, inflation-linked returns come close.
The payback figure the tool shows is the per-year cost divided by the per-year pension, so it stays the same whether you buy one year or several. Buying more years multiplies both the total cost and the total extra pension in lockstep, which is why the breakeven point does not move. Bear in mind the extra pension counts as taxable income, so if you are already above the £12,570 Personal Allowance in retirement, basic-rate tax shaves the net benefit a little, though the deal still stacks up comfortably.
Five years bought, modelled to breakeven
Using the defaults, buying five missing years at £907.40 each, here is how the numbers fall.
The chart tracks the cumulative extra pension against the £4,537 outlay. The lines cross just before the third year of retirement, and from there the pension keeps paying while the cost is fixed.
When topping up is the wrong move
Buying years is not always sensible. If you are still working and will naturally accrue the years you need before State Pension age, you would be paying for something you were going to get for free. If you already qualify for the full pension, extra years add nothing, so the contribution is simply wasted. And if you are entitled to NI credits, for example through Child Benefit or as a carer, claiming those credits is free and should always come before paying. The single most important step is to check your State Pension forecast and NI record on gov.uk first, and to call the Future Pension Centre before paying, because in a minority of cases an extra year genuinely does not increase your pension and they will tell you so.
Which years should I buy first?
Buy the cheapest qualifying years first, then the most recent. Some older years can be topped up at reduced rates, and there have been extended deadlines to fill gaps going back many years, so it is worth checking which specific years are available to you before sending money. The tool assumes a standard Class 3 rate, so adjust the cost input if HMRC quotes you a lower figure for a particular year.
Is the extra pension taxed?
Yes, the State Pension is taxable income, though it is paid without tax deducted at source. If your total income in retirement stays under the £12,570 Personal Allowance, you pay no tax on it. Above that, the extra you bought is taxed at your marginal rate, which trims the net return but rarely enough to change the decision.