ISA vs Pension Tax Relief 2027 Comparison UK
Compare ISA vs SIPP/workplace pension for 2026/27. See net cost, withdrawal tax, and total return at retirement with marginal-rate relief modelled.
| ISA net cost out-of-pocket | — |
| Pension net cost (after relief) | — |
| ISA fund value at retirement | — |
| Pension fund value at retirement | — |
| Pension 25% tax-free lump sum | — |
| Pension taxable withdrawal tax | — |
What Is the ISA vs Pension Trade-Off?
An ISA gives no upfront tax relief but tax-free withdrawals. A pension (SIPP or workplace) gives upfront tax relief at your marginal rate but taxes withdrawals (except the 25% Pension Commencement Lump Sum, capped at £268,275 by the Lump Sum Allowance). For higher-rate taxpayers who will drop to basic rate in retirement, the pension typically wins on after-tax return. For basic-rate taxpayers, ISA flexibility often wins.
How the 2026/27 Allowances Stack
ISA allowance is £20,000 per adult (frozen since 2017). Treasury has consulted on a £4,000 Cash ISA cap from April 2027 with the remaining £16,000 in stocks & shares — this comparison assumes existing rules. Pension annual allowance is £60,000 (or your earnings, whichever lower) with a tapered allowance down to £10,000 above £260,000 income. Carry-forward of 3 prior years available.
How to Decide
Use a pension if: you pay 40%/45% tax now and expect 20%/0% in retirement; employer matches contributions; you want to escape the £100k Personal Allowance taper. Use an ISA if: you pay basic rate now; you might need the money before 55/57; you want flexibility for early retirement bridging. Most people benefit from both — fill the workplace pension match first, then ISA, then top up SIPP.
Source and Disclaimer
Rates and allowances sourced from gov.uk and HMRC PTM as of May 2026. This is an educational calculator and is not regulated financial advice. Consult a chartered IFA before making major retirement decisions. Last updated: May 2026.
Source: gov.uk/government/collections/pensions-tax-manual