Your 2020/21 NI year disappears in April — here's what that actually costs you

There is a deadline in the UK pension system that no letter, no app notification and no employer will ever mention to you. Since the transitional window that allowed buying years back to 2006 closed in April 2025, voluntary National Insurance has reverted to its standing rule: you can fill gaps in your record for the last six tax years only. The consequence is a rolling annual expiry — every 5 April, the oldest open year shuts for ever.

Right now, the years from 2020/21 onwards are still buyable. On 6 April 2027, 2020/21 is gone. If you left the UK in 2020 or earlier and have paid nothing since, you are standing at the high-water mark of what can still be repaired — and the tide only goes out.

What one year is actually worth

The full new State Pension needs 35 qualifying years; each year is therefore worth roughly 1/35th of the pension — about £342 a year, for life, index-linked, from state pension age. Against that:

Class	Weekly	Cost per year bought	Payback period in retirement
Class 2 (most working expats)	£3.50	≈ £182	Under 7 months
Class 3 (everyone else)	£17.75	≈ £923	Under 3 years

Class 2 is available to expats who were employed or self-employed in the UK immediately before leaving and who work abroad — which describes most people reading this. There is no investment product on any shelf, anywhere, with that risk-adjusted return. The money is trivial; the eligibility window is what expires.

The one-sitting decision

Pull your NI record and State Pension forecast from your personal tax account (ten minutes, assuming your Government Gateway still works from abroad — a separate saga we've written up here).
Ignore the headline forecast — it assumes you keep contributing. Find the "based on your record so far" number and count your qualifying years against 35 (minimum 10 to get anything).
Check for contracted-out history. A COPE note on the forecast means your starting amount was adjusted — some people need more than 35 years, and occasionally a bought year adds nothing. This check is the difference between informed buying and hopeful buying.
Decide which back years to take. Not all gaps are equal: a year with partial credits can sometimes be completed for a fraction of the full price — the best value on the board.
File the CF83 for ongoing Class 2 and pay the chosen back years. Processing from abroad runs to months, which is precisely why the decision shouldn't wait for the March before an expiry.

Who should let years expire without regret

Anyone certain of reaching 35 clean years anyway — a 30-year-old planning decades of future UK employment is buying insurance they'll never claim. Anyone whose contracted-out arithmetic caps the benefit. And anyone who can't plausibly reach the 10-year minimum at all. Roughly one in five people we review shouldn't buy — which is exactly why the £149 review exists: we've priced telling you no at the same rate as telling you yes.

One more April is one more year gone. This is the rare tax decision where doing it this month rather than next spring has a hard, dated payoff.

A worked case, because the abstractions hide the money

Sarah left for Singapore in August 2021 after nine UK working years, and has paid nothing since. Her open gaps today: 2021/22 through 2025/26 — five years, all Class 2 eligible, roughly £900 the lot. Bought, they take her banked years from nine to fourteen; combined with ongoing Class 2 until state pension age she reaches the full 35 comfortably. The five back-years alone add about £1,710 a year to her eventual pension — £900 in, £1,710 out every year of retirement. Left another two years, 2021/22 and 2022/23 expire and that recoverable pension drops by nearly £700 a year, permanently. The gap between acting this year and 'sometime' is a compounding, dated, four-figure difference — which is rare in personal finance and worth treating with respect.

Questions readers ask

Can I still pay National Insurance for years before 2020/21?

No — the six-year window is a hard limit now that the transitional concession to 2006 closed in April 2025. Years older than six tax years are permanently unfixable, whatever you offer to pay. That is precisely why the annual 5 April expiry matters: each spring another year moves from 'buyable' to 'gone'. The one nuance worth checking is years that already carry partial credits from UK work, child benefit or credits you did not know you had — those are not 'missing years' at all and never needed buying. Pull the record before assuming anything about what is open.

How do I pay from abroad once my CF83 is approved?

HMRC issues a payment reference with the approval letter, and you pay by bank transfer — from a UK account if you kept one (easiest by far) or by international transfer to HMRC's account with the reference formatted exactly as instructed. Ongoing years can be set up as an annual direct debit from a UK account. Two practical warnings: transfers without the correct reference sit unallocated for months, and CF83 processing from abroad routinely takes eight to twenty weeks — so start the application well before the April deadline you care about, not the week of it.

Is buying NI years worth it if I might come back to the UK and work for years?

Often not — and this is the honest exception to the enthusiasm. Years you will fill anyway through future UK employment cost you nothing, so buying them now just hands HMRC money early. The calculation is: years already banked, plus realistic future UK working years, versus the 35 needed. If that sum comfortably reaches 35, save your money. If your return date is uncertain — which describes most expats we speak to — buying the cheap Class 2 back-years is inexpensive insurance against the plan changing.

What's the difference between the State Pension forecast and my NI record?

The forecast projects what you might get and usually assumes you keep contributing, which makes it dangerously optimistic for anyone who has left the UK. The NI record is the factual year-by-year ledger — full year, partial year, gap. Read the record for truth and the forecast only for the 'based on your record so far' figure and any COPE (contracted-out) note. The pairing of those two documents, read correctly and side by side, is the entire factual basis of a good buy-or-don't-buy decision on voluntary contributions.