ISA Growth Calculator UK 2026/27
Project your ISA growth over time and see how much you could save by keeping investments in a tax-free ISA wrapper.
Max £1667/month to use full allowance
Historical stock market average: 7-10%
After 10 Years
£100,134
Total Contributed
£70,000
Tax-Free Growth
£30,134
Compared to investing outside an ISA as a higher rate taxpayer
Calculation Methodology
Compound growth calculated monthly with contributions at month start. Tax savings compared against higher rate taxpayer (20% CGT, 33.75% dividend tax) with current year allowances. Past performance doesn't guarantee future results.
Official Sources
Important: Results are estimates based on standard HMRC rules. Your actual tax may differ based on your specific tax code, benefits, or HMRC adjustments. Always verify with your employer or a qualified accountant.
Frequently Asked Questions
What is the ISA allowance for 2026/27?
The ISA allowance is £20,000 per tax year for 2026/27. This is the total you can contribute across all ISA types (Cash ISA, Stocks & Shares ISA, Innovative Finance ISA, and Lifetime ISA). You can split this between different ISAs however you like.
How is ISA growth tax-free?
All growth within an ISA - whether from interest, dividends, or capital gains - is completely tax-free. You don't need to declare ISA income or gains on your tax return. This makes ISAs one of the most tax-efficient ways to save and invest in the UK.
Stocks & Shares ISA vs Cash ISA - which is better?
Cash ISAs are low risk but returns are limited by interest rates. Stocks & Shares ISAs offer potentially higher returns over the long term but with more volatility. For short-term savings (under 5 years), Cash ISAs are usually safer. For long-term goals, Stocks & Shares ISAs typically outperform.
Can I transfer ISAs between providers?
Yes, you can transfer ISAs to different providers without losing the tax-free status. Current year ISAs must be transferred in full, but previous years' ISAs can be partially transferred. Always use the official transfer process rather than withdrawing and re-depositing.
What happens to my ISA when I die?
Your spouse or civil partner can inherit your ISA's tax-free status through an Additional Permitted Subscription (APS). They can contribute an amount equal to your ISA value to their own ISA, on top of their normal allowance. This must be done within 3 years of death or estate administration.