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Compare modelled Stocks & Shares ISA and GIA outcomes under the same investment assumptions.
· UK investment tax illustration for 2026/27.
Restoring your saved ISA growth inputs…
Range £0 to £20,000.
Range £0 to £10,000,000.
Range £0 to £10,000,000.
Range £0 to £10,000,000.
£400,000 starting value plus contributions.
£400,000 starting value plus contributions.
ISA value minus GIA value; this is not tax saved.
The share link includes your financial assumptions in an unencrypted URL.
Same annual contribution and 20-year horizon. The GIA line includes yearly dividend tax and a one-off CGT estimate in the final year.
Year-by-year ending value (£; rounded to whole pounds)
| Year | ISA ending value | GIA after modelled taxes | Cumulative GIA tax |
|---|---|---|---|
| Year 1 | £21,420 | £21,420 | £0 |
| Year 2 | £44,361 | £44,229 | £132 |
| Year 3 | £68,930 | £68,485 | £435 |
| Year 4 | £95,244 | £94,282 | £921 |
| Year 5 | £123,427 | £121,717 | £1,600 |
| Year 6 | £153,610 | £150,894 | £2,485 |
| Year 7 | £185,936 | £181,923 | £3,589 |
| Year 8 | £220,558 | £214,922 | £4,926 |
| Year 9 | £257,638 | £250,017 | £6,511 |
| Year 10 | £297,350 | £287,340 | £8,359 |
| Year 11 | £339,882 | £327,032 | £10,488 |
| Year 12 | £385,433 | £369,245 | £12,915 |
| Year 13 | £434,219 | £414,138 | £15,659 |
| Year 14 | £486,469 | £461,881 | £18,740 |
| Year 15 | £542,428 | £512,656 | £22,179 |
| Year 16 | £602,360 | £566,654 | £25,999 |
| Year 17 | £666,548 | £624,081 | £30,225 |
| Year 18 | £735,293 | £685,154 | £34,882 |
| Year 19 | £808,919 | £750,105 | £39,997 |
| Year 20 | £887,772 | £741,345 | £123,434 |
Both wrappers receive the same new annual contribution; separate starting balances remain visible in the exact figures below.
Contributed capital and modelled outcome (£; rounded to whole pounds)
| Account | Starting value + new contributions | Ending value | Ending gap vs contributions |
|---|---|---|---|
| Stocks & Shares ISA | £400,000 | £887,772 | +£487,772 |
| General Investment Account | £400,000 | £741,345 | +£341,345 |
Recalculates both accounts at nearby annual price-growth rates while keeping contribution, horizon, dividend yield and tax-band assumption unchanged.
Growth sensitivity (£; rounded to whole pounds)
| Annual price-growth assumption | ISA ending value | GIA after modelled taxes |
|---|---|---|
| 3% | £699,204 | £608,031 |
| 5% | £887,772 | £741,345 |
| 7% | £1,134,423 | £915,025 |
The GIA estimate taxes gross dividends above the annual allowance at the selected rate, then estimates CGT once at terminal sale using one annual exempt amount.
GIA tax estimate (£; 2026/27 assumptions repeated; rounded to whole pounds)
| Component | Amount |
|---|---|
| Dividend tax across projection | £45,600 |
| Estimated CGT at terminal sale | £77,834 |
| Total modelled GIA tax | £123,434 |
Each annual contribution is added at the start of the modelled year. The model assumes one sale of the GIA at the end of the chosen horizon for its CGT estimate; this timing does not predict when you will invest or sell.
Valid URL values take priority per field. Missing or invalid fields use consented saved values, then the sample. Manage saved values in Export my data.
Compare Stocks & Shares ISA and General Investment Account (GIA) scenarios using the same annual investment amount and an explicit horizon.
Enter the same annual amount for both accounts, their separate starting values, the existing GIA cost basis, price-growth and dividend-yield assumptions, horizon and an assumed marginal tax band. The model reinvests dividends, estimates GIA dividend tax in each projection year, then estimates CGT once at a sale at the horizon using one annual exempt amount.
The starting GIA cost basis applies to existing holdings. During the projection, new contributions and reinvested dividends after modelled dividend tax increase the GIA basis. With a £0 starting basis, the model starts from no acquisition cost for existing holdings; terminal CGT is still based on final value minus accumulated basis and the annual exempt amount.
For 2026/27, the model uses a £20,000 annual ISA limit, a £500 dividend allowance in each modelled year, and one £3,000 CGT annual exempt amount at terminal sale. Its selected band rates are basic: 10.75% dividend tax / 18% CGT; higher: 35.75% dividend tax / 24% CGT; additional: 39.35% dividend tax / 24% CGT. It assumes current rules continue throughout the projection and reinvests dividends after modelled tax. It does not derive your tax band from other income or include Personal Allowance interactions, other dividends/gains/losses, fees, inflation, residence eligibility, allowance already used elsewhere or personal suitability. For Scotland, it does not derive the selected band from Scottish Income Tax bands; dividend and CGT rates are UK-wide. This is not a personal tax calculation, forecast or recommendation.
These official GOV.UK and FCA sources explain ISA and GIA tax treatment and investing risk. The projection is illustrative and does not replace personal tax or investment advice.