Relief at Source Pension Calculator 2026/27
See how much your pension provider tops up and whether you can claim additional relief through Self Assessment. Results update instantly.
Under relief at source, you pay pension contributions from your take-home (net) pay and your provider automatically adds 20% basic-rate tax relief. Pay in £800 and your pension is credited with £1,000 (divide any net payment by 0.8 to get the gross figure). If you are a higher- or additional-rate taxpayer, you claim the extra 20% or 25% relief yourself through Self Assessment — it is not added to your pot automatically.
How relief at source works
Relief at source is the most common method for personal pensions and SIPPs. When you make a contribution, you pay the net amount — 80% of the total. Your pension provider then claims the remaining 20% (basic rate tax relief) directly from HMRC, so your pension receives the full gross contribution.
If you pay income tax at the higher rate (40%) or additional rate (45%), you are entitled to further relief beyond the 20% that your provider claims. You must claim this yourself — either through a Self Assessment tax return or by asking HMRC to adjust your PAYE tax code.
The maths
Grossing-up formula: Gross contribution = Net payment ÷ 0.8
Provider top-up: = Net payment × 0.25 (= 25% of what you paid, or 20% of the gross)
Extra relief (40% taxpayer): = Gross contribution × (0.40 − 0.20) = 20% of gross
Worked example
James earns £55,000 and pays £800 into his SIPP. His income is above £50,270 so he is a higher-rate taxpayer.
- Gross contribution: £800 ÷ 0.8 = £1,000
- Provider top-up: £200 (20% of gross)
- Extra relief via SA: £1,000 × 20% = £200
- Total relief: £400
- Net cost to James after all relief: £600
Frequently asked questions
How does the provider know to claim basic rate relief?
When you set up a personal pension or SIPP under relief at source, your provider is registered to claim basic rate relief from HMRC. This happens automatically for every contribution you make — you don't need to do anything for the 20% top-up.
What is "grossing up"?
Grossing up converts your net payment to the gross contribution. If you pay £800, the gross is £800 ÷ 0.8 = £1,000. The formula works because you've paid 80% of the gross (the after-tax portion), and the provider claims the remaining 20% from HMRC.
Do I have to file Self Assessment to claim extra relief?
If you already file a Self Assessment return, you simply include your pension contributions in the relevant section. If you don't file one, you can contact HMRC directly and request a PAYE tax code adjustment — relief is then applied to your payslip going forward.
Does this apply to workplace pensions?
Only workplace pensions that use relief at source (usually NEST, People's Pension and some other modern workplace schemes). Many workplace pensions use the net pay arrangement instead — in that case, contributions are deducted before tax is applied and there is no provider top-up or SA claim involved.