UK Net Worth Projector: 10 to 30 Years of Pension, ISA and Mortgage
Project your UK net worth over 10, 20 or 30 years from pension, ISA and cash saving and mortgage paydown, using 2026/27 take-home pay and allowances.
Your starting position
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%
Existing pots
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£
£
£
Capped at the £20,000 a year ISA allowance for 2026/27.
£
What you add to cash after bills. Capped at what take-home pay leaves after ISA and mortgage payments.
Mortgage (optional)
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%
yr
Assumptions
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%
Above inflation. An assumption, not a forecast - try a lower figure too.
%
Trajectory
How the model works
- Pension contributions - your salary-sacrifice % is multiplied by gross salary each year. Employee contribution flows into the pension pot. Employer contribution NOT modelled (assume you set the total intended contribution as the salary-sacrifice % to keep the model simple).
- ISA contributions - your monthly £ saving is multiplied by 12 each year, capped at the £20,000 annual ISA allowance (2026/27).
- Cash savings - your monthly cash saving × 12 is added each year, capped at take-home pay minus ISA contributions and mortgage payments. Cash grows at the CPI rate (a real return of zero), and tax on savings interest is ignored.
- Invested assets - both pension + ISA grow at the real return compounded with CPI each year: the defaults (5% real, 2% CPI) give 7.1% nominal. Returns are your assumption; nothing here predicts them.
- Mortgage paydown - standard repayment formula. Monthly payment computed from balance, rate, term. Interest + principal split each year.
- Net worth = pension + ISA + cash − mortgage balance - the home's value is not modelled. To include it, add it to your starting cash (it will then grow at CPI).
2026/27 allowance limits
| Allowance | 2026/27 limit | Source |
|---|---|---|
| ISA annual allowance | £20,000 | Shared across cash, stocks and shares, innovative finance and Lifetime ISAs. |
| Pension Annual Allowance | £60,000 | Tapered down to a minimum of £10,000 where threshold income is over £200,000 and adjusted income is over £260,000. |
| Lifetime ISA contribution cap | £4,000 | Government 25% bonus = up to £1,000 a year. Counts within the £20,000 ISA allowance. |
| Junior ISA | £9,000 | Separate from the adult allowance. The money belongs to the child, who cannot withdraw it until 18. |
Important caveats
- Estimate only. Investment returns are not guaranteed; past returns are not indicative of future performance. The model assumes constant real returns each year - reality is sequence-of-returns risk dependent.
- Employer pension contribution is not separately modelled, and the % is treated as salary sacrifice (it reduces taxable pay and NI). To include an employer contribution, add it to the % - this slightly understates take-home, because the employer's part does not come out of your salary.
- Tax rates and thresholds are held at 2026/27 for every year. The Income Tax thresholds are frozen until April 2031; any later uprating, and any change to how salary sacrifice is treated, is not modelled.
- ISA and pension allowances are assumed unchanged for the whole projection. If they change, the caps the model applies will be wrong for those years.
- Mortgage modelled as simple repayment. Interest-only, offset, tracker mid-rate changes and overpayment strategies not modelled.
- Not financial advice. Decisions about pension, ISA, mortgage and asset mix should be made with regulated financial advice for your specific circumstances.