ISA Basics: Get tax-free savings and investing with our complete UK ISA Guide.
See how your ISA contributions could grow over time with our ISA calculator. Compare different contribution amounts, time horizons, and growth rates to plan your tax-free savings strategy.
ISA Allowance 2026/27
| ISA Type | Annual Limit | Lifetime Limit |
|---|---|---|
| Cash ISA | Up to £20,000 (shared) | None |
| Stocks & Shares ISA | Up to £20,000 (shared) | None |
| Innovative Finance ISA | Up to £20,000 (shared) | None |
| Lifetime ISA | £4,000 (counts towards £20,000) | Until age 50 |
| Total across all ISAs | £20,000 | None |
For full details on each ISA type, see our ISA guide.
ISA Growth Projections: Monthly Contributions
£200/month
| Years | Cash ISA (3.5%) | S&S ISA (5%) | S&S ISA (7%) | S&S ISA (10%) |
|---|---|---|---|---|
| 5 | £13,070 | £13,600 | £14,260 | £15,490 |
| 10 | £28,380 | £31,060 | £34,600 | £41,310 |
| 15 | £46,310 | £53,580 | £63,360 | £83,100 |
| 20 | £67,310 | £82,550 | £104,190 | £151,870 |
| 25 | £91,890 | £119,690 | £162,120 | £265,370 |
| 30 | £120,660 | £167,110 | £244,090 | £452,100 |
£500/month
| Years | Cash ISA (3.5%) | S&S ISA (5%) | S&S ISA (7%) | S&S ISA (10%) |
|---|---|---|---|---|
| 5 | £32,680 | £34,010 | £35,650 | £38,720 |
| 10 | £70,950 | £77,650 | £86,500 | £103,280 |
| 15 | £115,780 | £133,960 | £158,410 | £207,740 |
| 20 | £168,270 | £206,380 | £260,470 | £379,680 |
| 25 | £229,730 | £299,220 | £405,290 | £663,430 |
| 30 | £301,660 | £417,780 | £610,230 | £1,130,240 |
£1,000/month
| Years | Cash ISA (3.5%) | S&S ISA (5%) | S&S ISA (7%) | S&S ISA (10%) |
|---|---|---|---|---|
| 5 | £65,350 | £68,010 | £71,290 | £77,440 |
| 10 | £141,910 | £155,310 | £173,000 | £206,550 |
| 15 | £231,550 | £267,910 | £316,810 | £415,490 |
| 20 | £336,540 | £412,770 | £520,930 | £759,370 |
| 25 | £459,460 | £598,440 | £810,580 | £1,326,860 |
| 30 | £603,310 | £835,560 | £1,220,460 | £2,260,490 |
Max ISA: £1,666/month (£20,000/year)
| Years | Cash ISA (3.5%) | S&S ISA (5%) | S&S ISA (7%) | S&S ISA (10%) |
|---|---|---|---|---|
| 5 | £108,870 | £113,310 | £118,770 | £129,010 |
| 10 | £236,430 | £258,780 | £288,200 | £344,120 |
| 15 | £385,790 | £446,460 | £527,830 | £692,130 |
| 20 | £560,770 | £687,730 | £867,790 | £1,264,970 |
| 25 | £765,620 | £997,080 | £1,350,560 | £2,210,430 |
| 30 | £1,005,150 | £1,392,170 | £2,033,240 | £3,765,620 |
ISA vs Non-ISA: Tax Savings
Without an ISA, your investment gains are subject to tax:
| Tax Type | ISA | Non-ISA (Basic Rate) | Non-ISA (Higher Rate) |
|---|---|---|---|
| Interest income | Tax-free | 20% (above PSA) | 40% (above PSA) |
| Dividend income | Tax-free | 8.75% (above £1,000) | 33.75% (above £1,000) |
| Capital gains | Tax-free | 18% (above £3,000) | 24% (above £3,000) |
Tax Savings Example: £500/month for 20 Years (7% Return)
| Component | ISA | Non-ISA (Higher Rate) |
|---|---|---|
| Total contributions | £120,000 | £120,000 |
| Growth (before tax) | £140,470 | £140,470 |
| Tax on gains | £0 | ~£33,000 |
| Final value | £260,470 | ~£227,470 |
| Tax savings | — | £33,000 |
Lifetime ISA (LISA) Calculator
The LISA adds a 25% government bonus on top of your contributions:
| Monthly Contribution | Your Annual Total | Government Bonus | Total Annual | With Bonus After 10 Years (5%) |
|---|---|---|---|---|
| £100 | £1,200 | £300 | £1,500 | £19,430 |
| £200 | £2,400 | £600 | £3,000 | £38,860 |
| £333 (max) | £4,000 | £1,000 | £5,000 | £64,770 |
LISA Eligibility:
- Age 18-39 to open
- Contribute until age 50
- Use for first home (under £450,000) or retirement (after 60)
- 25% penalty on early withdrawal for other purposes
See Lifetime ISA vs Help to Buy ISA for a detailed comparison.
Which ISA Is Right for You?
| Goal | Best ISA Type | Why |
|---|---|---|
| Emergency fund (instant access) | Cash ISA | Capital protection, easy access |
| Short-term savings (1-3 years) | Cash ISA | Low risk, predictable returns |
| Medium-term (3-5 years) | Cash or S&S ISA | Balanced approach |
| Long-term wealth building (5+ years) | Stocks & Shares ISA | Higher expected returns |
| First home (age 18-39) | Lifetime ISA | 25% government bonus |
| Retirement supplement (age 18-39) | Lifetime ISA + S&S ISA | Bonus + long-term growth |
ISA Strategy Tips
| Strategy | Details |
|---|---|
| Use it or lose it | Allowance doesn’t carry over — contribute before 5 April |
| Start early | Even small contributions compound significantly over decades |
| Max your LISA first | 25% bonus is guaranteed return (if eligible) |
| Choose global index funds | Low-cost diversification for S&S ISA |
| Don’t time the market | Regular investing smooths out volatility |
| Review fees | Platform + fund fees compound against you over time |
Bottom Line
ISAs are one of the most powerful tax-free savings tools in the UK. Whether you use a Cash ISA for safety or a Stocks & Shares ISA for growth, the key is to start contributing regularly and take full advantage of your £20,000 annual allowance.
For more on saving and investing in the UK, see our guides on pensions, average savings by age, and the Stocks & Shares ISA guide.
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