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Class 2 vs Class 3 voluntary NI

If you're self-employed and have NI gaps, the choice between legacy Class 2 (£3.65 per week) and full-rate Class 3 (£17.75 per week) is the highest-leverage buy-back decision in the system - same year added to your record, but the cost differs by nearly 5x.

The cost gap, in one card

Class 2 weekly (legacy, self-employed)
£189.80 for a full year
£3.65 / wk
Class 3 weekly (general voluntary)
£923.00 for a full year
£17.75 / wk
Cost gap, per year of NI bought
Both buy the same single qualifying year, both add ~£6.89/wk to the new SP
£733.20

Pick Class 2 if

  • You were self-employed in the year you want to buy back, with profits below the Small Profits Threshold or with unrecorded SE activity HMRC can verify1.
  • The year falls in the legacy Class 2 window. Class 2 was abolished as a charge for most self-employed from 2024/25, but historic gap-years still settled at Class 2 rates if you were self-employed at the time2.
  • You can show HMRC the self-employment for the relevant year (Self Assessment record, accounts, or CWF1 history). HMRC will not retroactively let you reclassify a year as self-employed to grab the Class 2 rate.

Pick Class 3 if

  • You were an employee, abroad, or not working at all in the gap year. No Class 2 path is available3.
  • You were self-employed but never told HMRC, or your records won't stand up to scrutiny. Class 3 is the default fallback.
  • You want the simplest path with no HMRC self-employment evidence required. Class 3 is paid via gov.uk with no eligibility test beyond having the gap.

Worked example: same gap, two prices

Sara has a 2019/20 NI gap. She freelanced as a graphic designer that year, billed about £8,000, never registered for Self Assessment because profits were below the trading allowance.

Class 3 route: pay £923.00 now and the year counts. Adds about £6.89/wk to her new State Pension. Payback after SPA, about 2.6 years.

Class 2 route: register the self-employment retrospectively with HMRC (CWF1), evidence the £8,000 trading year, then pay the legacy Class 2 charge for 2019/20 of about £189.80. Same uplift, payback inside about 7 months. Saves £733.20 on a single year.

The trap: if Sara waits past the Class 2 payment deadline for that year (usually 31 January following the tax year, with an extended window for older years), she defaults to Class 3 pricing whether or not she was self-employed. Always check the gov.uk window before paying, and phone the Future Pension Centre to confirm the year will actually move her figure4.

Decision rules in priority order

  1. Were you self-employed in the year? If no → Class 3 only.
  2. Is the year still inside the Class 2 payment window? If no → Class 3 only.
  3. Can you evidence the self-employment to HMRC? If no → Class 3 by default.
  4. Does buying the year actually move your forecast? If no → don't pay either rate. Call the Future Pension Centre.
By Oliver Wakefield-Smith, Founder, Digital Signet.
Rates current for 2026/27 · Verified Q2 2026 · Next refresh after Autumn Budget 2026