What is the current ISA allowance?

The ISA allowance for the current tax year is £20,000, which can be split across different types of ISA or put entirely into one.

Does this include tax?

Growth and income inside an ISA are tax-free, so this calculator doesn't need to deduct any tax - the figures shown are the actual balance you'd have.

Why does the fee percentage matter so much over time?

Fees are charged every year, on the whole balance, so even a small percentage compounds against you the same way growth compounds for you - a 1% fee can meaningfully reduce the final balance over a long time horizon.

ISA Growth Calculator

Project how an ISA balance could grow with regular contributions and an expected annual return, net of fees. The current annual ISA allowance is £20,000.

Starting ISA Balance

Monthly Contribution

Expected Annual Return

Years

yrs

ISA growth

Estimated Final ISA Value

£89,026

Starting Balance£5,000

Amount Contributed£54,000

Estimated Growth£30,026

Final ISA Value£89,026

Year-by-year balance

Year 0

£5,000

Year 1

£8,937

Year 2

£13,065

Year 3

£17,393

Year 4

£21,931

Year 5

£26,690

Year 6

£31,680

Year 7

£36,912

Year 8

£42,398

Year 9

£48,150

Year 10

£54,181

Year 11

£60,506

Year 12

£67,137

Year 13

£74,090

Year 14

£81,381

Year 15

£89,026

Assumes a fixed annual return, net of fees, compounded monthly for the whole period. Real investment returns vary year to year. The current annual ISA allowance is £20,000.

How this projection works

This calculator compounds your starting ISA balance and each monthly contribution over the actual time it's invested, at your expected annual return net of any platform or fund fees - not a shortcut that just multiplies a return by the number of years.

The ISA allowance

The annual ISA allowance is £20,000 for the current tax year - the most you can pay into ISAs in total across all your ISAs. If your monthly contribution would add up to more than that over a year, the calculator flags it, since you wouldn't be able to shelter all of it inside an ISA wrapper.

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