Voluntary NI Contributions Calculator
The new State Pension is built entirely on qualifying years of National Insurance contributions or credits — you need 10 qualifying years for any State Pension at all, and 35 for the full amount. If your NI record shows gaps — often from time spent unemployed, abroad, on low earnings, or self-employed in a year with a small profit — you can usually pay voluntary contributions to fill them and increase your eventual pension.
There are two rates: Class 3, available to almost everyone with a gap, costs £18.40 a week in 2026/27 (£956.80 for a full year). Class 2, considerably cheaper at £3.65 a week (£189.80 for a full year), is restricted mainly to self-employed people whose profits fall below the small profits threshold and who'd otherwise have a gap year. Most people filling gaps will be paying the Class 3 rate.
Each qualifying year adds roughly £6.89 a week to your State Pension — about £358.50 a year — for the rest of your life once you start claiming. Because this is a recurring annual amount rather than a one-off payment, the payback period on a Class 3 year is typically short: £956.80 ÷ £358.50 works out to roughly 2.7 years of receiving your pension before the extra contribution has fully paid for itself, after which every further year of retirement is pure additional income.
Given that most people draw their State Pension for considerably longer than three years — often 15, 20, or more years in retirement — a Class 3 year bought today can realistically return several times its original cost over a typical retirement, making it one of the better-value, lowest-risk financial decisions available to most people with genuine gaps, especially compared with the returns available from many other guaranteed, risk-free savings products.
Under the standard rules, you can normally only fill gaps going back six tax years from the current one — a gap from 2019/20, for instance, would no longer be fillable once several years have passed beyond that window. A temporary extension previously allowed gaps back to 2006/07 to be paid, but that special extended window has now closed, so anyone with older gaps outside the standard six years has likely lost the chance to fill them, making it worth checking your NI record sooner rather than later if you suspect you have gaps.
Before paying anything, always check your State Pension forecast on gov.uk, which shows exactly which years are gaps, how much each specific year costs to fill (the price can vary year to year), and — crucially — whether you're already on track for the full 35 qualifying years without needing to pay anything at all. Paying to fill a year you didn't actually need would be money that adds nothing to your eventual pension.
Someone with three gap years, paying Class 3, faces a total cost of 3 × £956.80 = £2,870.40. Those three years add 3 × £6.89 = £20.67 a week to their eventual State Pension, or £1,075.50 a year. The payback period is £2,870.40 ÷ £1,075.50, which works out to roughly 2.7 years of receiving the pension before the cost is fully recovered.
Assuming a typical 20-year retirement drawing the State Pension from age 67, the total extra income received from those three filled years is £1,075.50 × 20 = £21,510 — against an upfront cost of £2,870.40, a net lifetime gain of roughly £18,640 (before accounting for the pension's own annual increases under the triple lock, which would likely make the real figure meaningfully higher still, since the £358.50-per-year figure is fixed at today's rate rather than rising each year alongside the rest of the pension).
If the same three years could be filled at the cheaper Class 2 rate (for an eligible self-employed person), the total cost would be just 3 × £189.80 = £569.40 — payback in well under a year, and a lifetime gain of roughly £20,940 on the same 20-year assumption, illustrating just how much cheaper Class 2 is when someone is eligible for it.
Voluntary NI isn't automatically worth it for everyone. If you're already on track for 35 qualifying years by State Pension age — through employment, self-employment, or NI credits from certain benefits, caring responsibilities, or National Insurance credits for parents and carers — additional years add nothing extra to the new State Pension, since it's capped at the full rate once 35 years are reached. Paying for a year you don't need is simply money given away.
It's also worth checking whether you might already qualify for NI credits rather than needing to pay — certain periods of unemployment while claiming benefits, time spent as a carer, or receiving Child Benefit for a child under 12 can all generate qualifying years automatically, at no cost, and these should be checked and applied for before considering a voluntary payment for the same period. Finally, anyone very close to State Pension age with only a few years of retirement genuinely expected should run the payback-period math carefully rather than assuming it's automatically worthwhile, since a very short remaining life expectancy changes the calculation considerably.
Before paying anything, get your State Pension forecast through the "Check your State Pension" service on gov.uk, or via the HMRC app — both show your current qualifying years, any gaps, and, crucially, the exact price to fill each specific gap year, since the cost can vary depending on how old the gap is and whether special transitional rates ever applied to it. This forecast also tells you directly whether you're already projected to reach the full 35 years without paying anything, which is the single most important check before spending any money.
If a gap is genuinely worth filling, you can usually pay directly online through the same government service, by phone, or by bank transfer using the 18-digit reference number HMRC provides — the Future Pension Centre can also talk through your specific record if the online forecast raises questions about eligibility or which years are the best value to fill first. It's generally sensible to fill the cheapest, most recent gaps first, since older gaps within the six-year window may be more expensive or approaching the point where they drop out of the fillable window altogether.