UK Net Worth Projector
Year-by-year projection of net worth combining salary, pension contributions, ISA savings, and (optionally) mortgage paydown. Uses verified 2026/27 UK tax rules + ISA / pension allowance limits.
Your starting position
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Existing pots
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Max £1,667/mo = £20,000/yr ISA allowance 2026/27.
Mortgage (optional)
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Assumptions
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Above inflation. FTSE All-Share long-run ~5%; conservative mix ~4%.
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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 - take-home pay minus ISA contribution leaks into cash which grows at the CPI rate (i.e. real return zero - cash erodes against inflation).
- Invested assets - both pension + ISA grow at "real return + CPI" (nominal) each year. Default 5% real + 2% CPI = 7% nominal. Vanguard FTSE Global All Cap inception-to-date is approximately 7-9% nominal.
- Mortgage paydown - standard repayment formula. Monthly payment computed from balance, rate, term. Interest + principal split each year.
- Net worth = pension + ISA + cash + property equity - property equity is NOT modelled because we don't have house value. To approximate, treat your home value as "cash savings" and the mortgage balance reduces it.
Verified 2026/27 allowance limits
| Allowance | 2026/27 limit | Source |
|---|---|---|
| ISA annual allowance | £20,000 | Frozen since 2017/18. Includes Cash + Stocks & Shares + Innovative Finance + Lifetime ISA sub-cap. |
| Pension Annual Allowance | £60,000 | Raised from £40,000 in April 2023, unchanged since. Tapered to £10,000 for very high earners. |
| Lifetime ISA contribution cap | £4,000 | Government 25% bonus = up to £1,000/year. Counts within main £20,000 ISA allowance. |
| Junior ISA | £9,000 | Separate from adult ISA. Owned by child, locked 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 NOT separately modelled. Most UK workplaces add 3-10% on top of your salary sacrifice. Enter the total intended pension % (yours + employer match) to get a more accurate pot.
- Tax rates frozen at 2026/27. Real-world tax bands may uprate after the legislated 2027/28 freeze ends - this is unmodelled.
- ISA + pension allowances assumed unchanged. Both are frozen in cash terms; if uprated in future the projections underestimate compound.
- 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.