CalcBritain

Pension vs ISA Calculator

Put the same amount of your take-home pay into a pension or an ISA each month and see which wins — after tax relief, growth, an optional employer match, and tax on the way out.

Estimate only. This calculator gives estimates for information only, not financial advice. Pension and ISA rules, allowances and your own tax position can materially change these results — consider speaking to a regulated financial adviser before making a decision.

Enter a monthly amount

Your pension and ISA pots, and which one wins, appear here as you type.

The classic conclusions

  • • Higher-rate now, basic-rate in retirement: the pension usually wins by a large margin — you get 40%+ relief going in but only pay 20% coming out.
  • • Basic-rate now and basic-rate in retirement: the pension still tends to edge ahead, purely because 25% of the pot comes out completely tax-free.
  • • If you'd spend any extra tax relief you reclaim rather than reinvest it, a higher earner's real-world pension advantage is smaller than the headline numbers suggest.
  • • Under 40? A Lifetime ISA is a third option worth considering alongside these two — it adds a 25% government bonus like a pension, but stays as flexible and tax-free as an ISA (with restrictions on when you can access it penalty-free). See the Lifetime ISA calculator for the numbers.

Pension or ISA — how the tax wrappers differ

A pension gives tax relief on the way in (and usually an employer match — always take that first), but withdrawals beyond the 25% tax-free lump sum are taxed as income and locked away until at least 55–57. An ISA is funded from taxed income but everything comes out tax-free, whenever you like. If your tax rate now is higher than it will be in retirement, the pension usually wins; the ISA’s prize is flexibility.