Stocks & Shares ISA Growth Calculator 2026-27
Making the most of your tax-free savings allowance.
Project the growth of your ISA over time. Tax-free compound growth on up to £20,000/year. Enter your monthly contribution, expected return, and time horizon. Covers both Cash ISA and Stocks and Shares ISA scenarios.
Returns not guaranteed. Past performance does not predict future returns.
How UK ISAs work and grow tax-free
ISAs (Individual Savings Accounts) are the UK's primary tax-free savings and investment wrapper. Understanding how allowances, transfers, and compounding work is essential to maximising long-term returns.
The ISA tax advantage
In a general investment account (GIA), dividends are taxed (8.75-39.35%) and capital gains above £3,000 attract CGT (18-24%). In an ISA, all returns are tax-free forever. Over 20 years at 7% return with £500/month: ISA gives ~£261,000, GIA after tax gives ~£220,000 — a £41,000 ISA advantage.
Annual allowance mechanics
£20,000 per UK adult tax year (6 April - 5 April). Unused allowance is lost, not carried forward. From April 2024 you can open and subscribe to multiple ISAs of the same type (e.g. two Cash ISAs) in one tax year, provided total doesn't exceed £20,000.
ISA transfers between providers
Can transfer without affecting allowance — use the provider's transfer form, never withdraw and redeposit. Takes 15-30 days typically. Partial or full transfers allowed. Transfer between types (Cash to S&S or vice versa) is permitted.
Flexible vs non-flexible ISAs
Flexible ISAs allow you to withdraw and redeposit within the same tax year without affecting your allowance. Not all ISAs are flexible — check the terms. Useful for emergency access without penalty.
UK ISA allowance limits 2026-27 by type
ISA subscription limits
| ISA type | 2026-27 limit | Notes |
|---|---|---|
| Cash ISA | £20,000 (combined) | Instant, fixed, or regular saver |
| Stocks & Shares ISA | £20,000 (combined) | Shares, funds, ETFs, bonds |
| Innovative Finance ISA (IFISA) | £20,000 (combined) | P2P lending |
| Lifetime ISA (LISA) | £4,000/year | Counts toward £20,000; 25% bonus |
| Junior ISA (JISA) | £9,000/year | Separate — for under-18s |
Combining ISAs within the allowance
You can split £20,000 across different ISA types. Example: £4,000 LISA + £5,000 Cash ISA + £11,000 S&S ISA = £20,000 used. LISA counts within £20,000. JISA is separate (can contribute £9,000 to a child's JISA and also £20,000 to your own adult ISA).
Historical ISA allowance changes
| Tax year | ISA allowance |
|---|---|
| 1999-2017 (ISAs introduced 1999 at £7,000) | Gradually raised |
| 2017-18 onwards | £20,000 (held steady) |
| JISA 2024-25 onwards | £9,000 |
Types of UK ISA compared: Cash, S&S, Lifetime, Junior
Cash ISA
Savings account with tax-free interest. Current rates 4-5%, broadly tracking the Bank of England base rate. FSCS-protected to £85,000. Easy access, notice, or fixed-term versions. Best for: emergency funds, short-term goals, and savers close to or above the Personal Savings Allowance.
Stocks & Shares ISA
Investment wrapper for shares, funds, ETFs, bonds, investment trusts. All gains and dividends tax-free. Historic returns ~7% per year (FTSE All-Share). Capital can fall. Best for: 5+ year horizons where volatility can be tolerated.
Lifetime ISA (LISA)
£4,000/year limit with 25% government bonus (max £1,000/year). For first home (up to £450,000 property) or retirement from age 60. Open aged 18-39. 25% penalty on withdrawals for other reasons. Most valuable ISA for first-time buyers.
Innovative Finance ISA (IFISA)
Peer-to-peer lending within ISA wrapper. Typical rates 4-8%. Higher risk than cash — no FSCS protection on the underlying loans. Best for: experienced investors willing to lend to businesses or individuals.
Junior ISA (JISA)
£9,000/year for children under 18. Cash or Stocks & Shares. Locked until child's 18th birthday (then becomes standard adult ISA). Tax-free growth builds a meaningful fund by adulthood. Grandparents, aunts, uncles can contribute.
Help to Buy ISA (closed to new savers)
Closed to new accounts November 2019 but existing accounts continue. 25% bonus on savings up to £12,000 for first home. LISA is generally a better option for new savers with higher limits and more flexibility.
UK ISA growth projections
£200/month at 6% return in ISA
| Years | Contributed | Final value | Tax-free growth |
|---|---|---|---|
| 10 | £24,000 | £32,800 | £8,800 |
| 20 | £48,000 | £92,400 | £44,400 |
| 30 | £72,000 | £201,900 | £129,900 |
| 40 | £96,000 | £398,000 | £302,000 |
Maxed ISA: £20,000/year at 6%
| Years | Contributed | Final value |
|---|---|---|
| 10 | £200,000 | £279,000 |
| 20 | £400,000 | £779,000 |
| 30 | £600,000 | £1,676,000 |
LISA: £4,000/year + 25% bonus
Contributing £4,000/year from age 18-49 (31 years): total contributed £124,000 + £31,000 bonus = £155,000 invested. At 6% growth: final value ~£415,000 at age 50. At age 60: ~£740,000 untouched.
FAQFrequently asked questions about UK ISAs
Can I have multiple ISAs?
From April 2024, yes — you can pay into multiple ISAs of the same type in one tax year. Total across all ISAs capped at £20,000. Before 2024, you could only pay into one of each type per year.
What happens to my ISA if I move abroad?
Existing ISA keeps its tax-free status in the UK. You can't subscribe to a new ISA or add to existing once non-resident. Other countries may tax ISA returns — consult local tax rules.
Should I use Cash ISA or Stocks & Shares ISA?
Cash for short-term (under 5 years) and emergency funds. Stocks & Shares for long-term (5+ years) where you can ride out volatility. Many people use both — cash for emergency fund, S&S for long-term wealth building.
Do I pay tax on ISA withdrawals?
No. ISA withdrawals are entirely tax-free at any time for Cash and Stocks & Shares ISAs. Lifetime ISA: 25% penalty on withdrawals before age 60 unless for a first home.
What happens to ISA on death?
Spouse inherits an Additional Permitted Subscription equal to the ISA value — preserving tax-free wrapper. ISA itself remains tax-free until 3 years after death or estate wrap-up. After that, gains are taxable.
Are ISA returns guaranteed?
Cash ISAs: interest guaranteed for fixed terms, variable for easy access. FSCS-protected to £85,000. Stocks & Shares ISAs: no guarantee — values fluctuate with markets. Historic average 7% but individual years can be negative.
Where these figures come from
Savings and interest figures on this page are drawn from The Bank of England (Bank Rate), HMRC (ISA and savings tax rules), the Financial Services Compensation Scheme (deposit protection), and the Financial Conduct Authority (consumer protection).
- Bank Rate (base rate) — Bank of England — The Interest Rate (Bank Rate).
- ISA annual allowance & rules — GOV.UK — Individual Savings Accounts (ISAs).
- Personal Savings Allowance — GOV.UK — Tax on savings interest.
- FSCS deposit protection (£85,000) — FSCS — Financial Services Compensation Scheme.
- Consumer money guidance — MoneyHelper — Savings.
Last checked: April 2026. Rates and thresholds are reviewed against the source of record each November, when annual adjustments for the following tax year are published.
Select the question that matches where you are right now.
Your result shows the projected growth or return based on the rate, contribution, and time period you entered — using standard compound or simple interest formulas.
Use this to set savings targets, compare investment options, or understand the impact of starting earlier. Adjust the rate and timeframe to model optimistic and conservative scenarios.
Not a guaranteed return. Actual investment outcomes depend on market conditions, fees, taxes, and timing that cannot be predicted with certainty.
Uses standard financial formulas with the inputs you provided. All calculations run in your browser — no data is sent to any server.
Savings and investment results are dominated by three factors: the rate of return, the time horizon, and regular contributions. Compounding amplifies all three over time.
Returns on returns accelerate growth over time. The difference between 5% and 7% over 20 years is much larger than the 2% gap suggests — compounding is non-linear.
Adding even small regular amounts dramatically increases the final balance. £100/week invested at 7% for 20 years grows to over £110,000 in contributions and £110,000+ in returns.
Starting 5 years earlier often produces a larger final balance than doubling your contribution rate. Time is the most powerful variable in savings calculations.
To improve your savings outcome, focus on starting earlier, increasing contributions, and minimising fees and tax drag on returns.
Starting with a small amount today and increasing over time beats waiting to start with a larger amount. Time in the market matters more than timing the market.
A 1% annual fee on a £100k balance costs £1,000/year and compounds against you. Compare fee structures across savings and investment products.
Super, offset accounts, and tax-free thresholds reduce the drag of tax on your returns — letting more of the growth compound for you.
Savings decisions connect to investment, tax, and retirement planning. Use these calculators to model the broader picture.
Work backwards from a target amount to see how much you need to save each month.
Savings goal →Model how an initial investment grows with regular contributions over different time periods.
Compound interest →See what your future balance is worth in today's dollars after adjusting for inflation.
Inflation calculator →