Junior ISA Calculator UK 2026

Junior ISA Growth Calculator

Child's Current Age (years)

Current JISA Balance (£)

Annual Contribution (£, max £9,000)

Expected Annual Return (%)

JISA Type

Value at Age 18

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Total projected value

Total Contributed

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Your money in

Growth / Returns

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Tax-free compound gain

Return Multiple

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Value vs money in

Value at Key Ages

Year-by-Year Growth Table

Age	Opening Balance	Contribution	Growth	Closing Balance

Junior ISA Provider Comparison 2026

Provider	Type	Annual Fee	Min Contribution	Notes
Vanguard	Stocks & Shares	0.15% (max £375/yr)	£1/month	Index funds only; very low cost
Hargreaves Lansdown	Stocks & Shares	0.45% (capped £45/yr funds)	£25/month	Wide fund choice; good app
OneFamily	Stocks & Shares	1.5% all-in	£10/month	Ethical fund option
AJ Bell	Stocks & Shares	0.25% (max £100/yr)	£25/month	Good for ETFs and funds
Coventry BS	Cash	0%	£1	Competitive cash rate; check current AER
Nationwide	Cash	0%	£1	Easy transfers; competitive rate
Bath BS	Cash	0%	£1	Historically top cash rates

Rates and fees correct at time of writing. Always check the current rate directly with the provider before opening. You can transfer a JISA to a different provider at any time.

Cash JISA vs Stocks & Shares JISA

Feature	Cash JISA	Stocks & Shares JISA
Typical return (2026)	4–5% AER	6–10% per year (historical average)
Risk of loss	None (FSCS protected up to £85k)	Yes — value can fall short-term
Best for	Short timeframes; risk-averse	Long timeframes (5+ years)
Inflation protection	Partial (rate may lag inflation)	Better over long run
Tax	Tax-free	Tax-free
Fees	Usually zero	0.15–1.5% per year
Investment choice	None	Funds, ETFs, shares (varies by provider)
Flexibility	Can switch to S&S JISA anytime	Can switch to Cash JISA anytime

Rule of thumb: For children under 12 with 6+ years to go, a Stocks & Shares JISA in a global index tracker (e.g. FTSE Global All Cap, Vanguard LifeStrategy 80%) has historically produced significantly better outcomes than cash. For children aged 15–17, consider switching some holdings to cash to protect gains as age 18 approaches.

Junior ISA Guide — Rules, Tips & How Compound Growth Works

A Junior ISA (JISA) is a long-term, tax-free savings or investment account for children in the UK. Parents or legal guardians open the account; the child cannot access the money until they turn 18. No income tax or capital gains tax applies to growth inside a JISA — making it one of the most powerful savings vehicles available for building a financial foundation for your child.

JISA Annual Allowance 2025/26

The Junior ISA annual allowance is £9,000 per tax year (unchanged since 2020/21). This limit applies per child, and can be split between a Cash JISA and a Stocks & Shares JISA as long as the combined total does not exceed £9,000. For example, you could put £4,000 in a Cash JISA and £5,000 in a Stocks & Shares JISA in the same tax year.

Who Can Open a Junior ISA?

A JISA can be opened by a parent or legal guardian for a child who is under 18 and a UK resident. The child cannot open their own JISA (though they can manage it from age 16). Grandparents, other relatives and friends can all contribute once the account is open — subject to the £9,000 annual cap in total from all sources.

The Power of Starting Early — Compound Interest Examples

The single most impactful decision with a JISA is starting as early as possible. At 7% annual return:

£100/month from birth: £18 years x £1,200 = £21,600 contributed — projected value at 18: approximately £43,000+
£100/month from age 5: 13 years x £1,200 = £15,600 contributed — projected value at 18: approximately £26,000
£100/month from age 10: 8 years x £1,200 = £9,600 contributed — projected value at 18: approximately £13,800

Starting at birth versus age 10 with the same monthly amount gives more than three times the final value. The five years at the beginning are the most valuable due to compounding on the earliest contributions.

What Happens When the JISA Matures?

On the child's 18th birthday, the JISA automatically becomes a standard adult Cash ISA or Stocks & Shares ISA. The former child (now an adult) takes full control. They can keep contributing (using their £20,000 adult ISA allowance), leave it invested, withdraw the money, or transfer it. The JISA balance does not affect their £20,000 ISA allowance for that tax year.

Child Trust Funds (CTF) and Transferring to a JISA

Children born between 1 September 2002 and 2 January 2011 may have a Child Trust Fund (CTF) rather than a JISA. CTFs and JISAs cannot both be held at the same time, but parents can transfer a CTF to a JISA at any time. This is usually beneficial if the JISA offers better rates or lower fees than the CTF.

Index Trackers in a Stocks & Shares JISA

The most popular investments in Stocks & Shares JISAs are global index tracker funds. The Vanguard FTSE Global All Cap Index Fund and FTSE All-World ETF are widely recommended by financial experts for their diversification, low cost and long-term track record. Vanguard's own JISA charges just 0.15% per year (platform fee plus fund charge), making it one of the most cost-effective options available.

Junior ISA Frequently Asked Questions

What is the Junior ISA allowance for 2025/26?

The Junior ISA (JISA) annual allowance is £9,000 per tax year for 2025/26. This applies per child and can be split between a Cash JISA and a Stocks & Shares JISA. Combined contributions from all sources (parents, grandparents, relatives) must not exceed £9,000 in any single tax year.

When can a child access their Junior ISA?

A Junior ISA cannot be accessed until the child turns 18. At that point it automatically converts to an adult ISA. The child can manage the account (change investments, add to it) from age 16 but still cannot withdraw until 18. There are no early access provisions except in very limited circumstances such as terminal illness.

Should I choose a Cash JISA or Stocks & Shares JISA?

Cash JISAs offer guaranteed returns at current rates (typically 4-5% in 2026) with no risk of loss. Stocks & Shares JISAs have historically returned 7-10% per year over long periods with short-term volatility. For young children with many years until access, a Stocks & Shares JISA in a global index tracker is generally recommended for its long-term growth potential and inflation protection.

Which providers offer the best Junior ISA in 2026?

Top Stocks & Shares JISA providers include Vanguard (0.15% annual fee, excellent for passive investing), Hargreaves Lansdown (wider choice, 0.45% capped at £45/year for funds), and AJ Bell (0.25% capped at £100). For Cash JISAs, check Coventry Building Society, Nationwide and Bath Building Society for current top rates. Always compare fees and returns before opening.

Can grandparents pay into a Junior ISA?

Yes. Anyone can contribute to a child's Junior ISA — grandparents, relatives and friends can all pay in. The account must be opened by a parent or legal guardian. Once open, contributions from all sources combined must not exceed the £9,000 annual allowance. This makes the JISA an ideal vehicle for family gifting with a long-term purpose.

What happens to a Junior ISA when the child turns 18?

When a child turns 18, the Junior ISA automatically converts to an adult ISA (Cash or Stocks & Shares depending on JISA type). The young adult can then access and manage it freely. The matured JISA balance does not count against their £20,000 adult ISA allowance for that tax year, giving them a valuable financial head start.

Is there any tax to pay on Junior ISA growth?

No. There is no income tax on interest or dividends, and no capital gains tax on investment growth inside a JISA. This tax-free status makes the JISA particularly powerful for long-term compounding — every penny of growth stays in the pot, dramatically increasing the final value compared with a taxable account.