Saving & investing

Pension vs ISA vs Mortgage Overpayment Calculator

These choices can produce very different future numbers because tax treatment, access, investment risk and mortgage interest work differently. The largest projected number is not automatically the right choice for your circumstances.

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Amount and horizon

Use the same cash commitment across the three routes.

£/month
years
%/year
%/year

Pension and mortgage assumptions

Model the structural differences.

%
Enter the gross uplift relative to the cash amount you give up.
£/month
£
%
years

Your estimate

Use the result as a planning guide and change inputs to test the assumptions that matter most.

Use the result as a planning guide and change inputs to test the assumptions that matter most.

How this calculator works

The investment routes use compound-growth assumptions. The pension route increases the monthly contribution using the uplift and employer amount you enter. The mortgage route amortises the loan with and without the extra monthly payment and reports modelled interest and time saved.

How to use it

  1. Choose a monthly amount and time horizon.
  2. Enter a cautious investment return and fee.
  3. Add only pension uplift/match you genuinely expect.
  4. Enter mortgage balance, rate and remaining term.
  5. Compare liquidity, risk and access as well as the modelled values.

Assumptions and limitations

Investment returns are not guaranteed. Pension tax treatment and access rules can change and depend on circumstances. Mortgage overpayment rules and early repayment charges vary by lender.