How much can I put into a Junior ISA this year?

£9,000 in 2026/27, across a cash Junior ISA and a stocks and shares Junior ISA together — a child can hold one of each and the limit is shared between them. Anyone can pay in, so contributions from grandparents and godparents count against the same figure. The allowance is per tax year and does not carry forward: whatever is unused on 5 April cannot be used later, and a fresh £9,000 starts on 6 April.

Does a Junior ISA use up my own ISA allowance?

No. The Junior ISA limit belongs to the child and sits entirely outside your own £20,000. You can pay £9,000 into a child's account and still subscribe the full £20,000 to your own ISAs in the same tax year. gov.uk puts it plainly: parents or guardians with parental responsibility can open and manage the account, but the money belongs to the child.

What happens when the child turns 18?

The account matures and the money becomes theirs to withdraw, in full, whenever they like, for anything at all. There is no condition attached — not university, not a house deposit, not driving lessons. Nobody who paid in has any say in it, and there is no mechanism to attach one. That is the single most important fact for anyone deciding how much to put in, and it is why this calculator shows the balance at 16 as well as at 18.

Can the child take the money out before 18?

No — and this is the one place a Junior ISA is stricter than an ordinary savings account. The money is locked until the account matures, for the child as well as for you. Withdrawals before then are allowed only in narrow circumstances: terminal illness, or closing the account on death. At 16 the child takes over managing the account — choosing the investments, moving the provider — but that is control, not access.

Do I pay tax on a Junior ISA?

No. No income tax on interest, no tax on dividends, no capital gains tax on growth, and nothing for you or the child to declare, however large the account grows. The shelter matters more than it looks: outside a Junior ISA, income produced by money a parent gave a child is taxed on the parent once it passes a set amount in a year — the whole of it, not just the excess. That rule has no application to a Junior ISA at all.

Is the projection on this page a forecast?

No. It is arithmetic on the growth rate you entered: what that rate would produce if it held exactly, every period, until the account matures. Nothing published by government goes into it, nobody knows what returns will be, and real returns arrive in an order that changes the answer even when the average is the same. The Junior ISA limit beside it is a different kind of figure — that one is published, and it is checked against gov.uk.

Cash or stocks and shares?

This page projects one balance at one growth rate you choose, so it will not answer that for you and neither will any calculator — the rate is the assumption, not the output. What it can show is how much the choice of rate matters over the term you actually have, which for a young child is close to 18 years. Change the growth rate and watch the balance at maturity move. A child can hold one cash Junior ISA and one stocks and shares Junior ISA at the same time, sharing the single limit between them.

Does the money in the account count towards the allowance?

No — only new money paid in during the tax year. Growth inside the account never uses allowance, and neither does a transfer from another Junior ISA or from a Child Trust Fund. An account already worth many times the annual limit can still take a full £9,000 subscription this year.

What if I pay in more than the limit?

Tell the provider rather than waiting. HMRC identifies over-subscriptions after the tax year ends and removes the excess, so the money spends months looking sheltered when it is not. This calculator reports the excess rather than quietly capping the figure, because a tidy answer would hide the thing you need to act on.

Junior ISA calculator 2026/27 — what it grows to, and when it stops being yours

The Junior ISA

Already in the account

What it is worth today, including growth and money paid in during earlier tax years. Only new money uses this year’s allowance, so a balance built up over a decade uses none of it.

Adding each period

New money paid in every month, at the start of the period. Anyone can pay in — grandparents included — and it all counts against the same limit.

How often

Growth a year

Total return before charges. It is a nominal rate — nothing on this page is adjusted for inflation. Nobody knows this number; you are choosing an assumption, and the projection is arithmetic on it.

Annual charges

Platform and fund charges together, taken from the account each period. Over a term this long they compound against you as reliably as the growth compounds for you.

The child, and the tax year

The child’s age now

Whole years. This is what sets the term: the account runs until they turn 18, which from here is 13 years. There is no age 18 to enter, because at that point it is not a Junior ISA any more.

Tax year

Which year’s Junior ISA limit the contributions above are measured against. The projection itself uses no tax year — nothing inside the account is taxed.

This is the child’s allowance, not yours. Paying into a Junior ISA uses none of your own £20,000. Where your allowance has gone is the ISA allowance calculator.

Nothing you type is transmitted or stored: this page is a static file and the arithmetic runs in this tab. A share link is the exception — it carries your figures in the URL. What that means.

The projection, and the two ages that end your say in it

In 13 years, on their 18th birthday, this projection ends at

£24,887.23

This is not a forecast. It is what 5.00% a year would produce if it held exactly, every month, for 13 years. Real returns arrive as a sequence and the order changes the answer. Nobody can tell you the rate — you typed it, and no rate, threshold or allowance published by government goes into this number.

Of the £9,000 a Junior ISA can take in 2026/27, your contributions leave

£7,800.00

And on 6 April it is gone. A Junior ISA allowance does not carry forward: whatever is unused when the tax year ends cannot be used later, and a fresh £9,000 starts instead. £1,200.00 of the limit is used at the rate above.

That limit is statutory. It is a published figure, checked against gov.uk and dated in the methodology below, and it belongs to the child rather than to whoever pays in — so it uses none of your own £20,000. What has not been verified is any answer on this page.

Two dates, and neither of them is yours

This is the part a projection to 18 leaves out. A Junior ISA is the child’s money from the first payment, and it changes hands twice on a timetable nobody paying in can alter.

What happens at each age, and what the account is projected to hold
Age	What changes	Projected balance
16	In 11 years the child becomes the registered contact and manages the account. You stop being able to change the investments or move the provider; they can. They still cannot take the money out.	£20,433.20
18	The account matures and the money is theirs to withdraw, in full, on any day they choose, for anything at all. There is no condition on it — not university, not a deposit, not a car. It is simply theirs.	£24,887.23

£2,400.00 of what you pay in lands in an account they already manage. That is the contributions from age 16 onwards. It is not an argument against paying in — it is the fact worth knowing before the standing order rather than after the 16th birthday.

Year by year, against their age

The projection rolled up by year, with the age the child reaches at the end of each
Age at the end	Opening	Paid in	Growth	Charges	Closing
6	£2,000.00	£1,200.00	£132.07	−£9.49	£3,322.58
7	£3,322.58	£1,200.00	£198.07	−£14.24	£4,706.41
8	£4,706.41	£1,200.00	£267.16	−£19.21	£6,154.36
9	£6,154.36	£1,200.00	£339.44	−£24.40	£7,669.40
10	£7,669.40	£1,200.00	£415.08	−£29.83	£9,254.65
11	£9,254.65	£1,200.00	£494.19	−£35.52	£10,913.32
12	£10,913.32	£1,200.00	£577.03	−£41.48	£12,648.87
13	£12,648.87	£1,200.00	£663.65	−£47.71	£14,464.81
14	£14,464.81	£1,200.00	£754.29	−£54.22	£16,364.88
15	£16,364.88	£1,200.00	£849.13	−£61.04	£18,352.97
16 — they take control	£18,352.97	£1,200.00	£948.39	−£68.16	£20,433.20
17	£20,433.20	£1,200.00	£1,052.23	−£75.64	£22,609.79
18 — it matures	£22,609.79	£1,200.00	£1,160.88	−£83.44	£24,887.23

The schedule runs in months and is rolled up to a year a row, so a row’s closing balance is the balance on that birthday. Contributions are £100.00 a month paid at the start of the period, and the rate is an AER — 5.00% a year compounds to exactly 5.00%, not to more. The periodic rate the schedule actually used is 0.4074%.

How the pot is made up

The four lines above the total add up to the balance at maturity
Already in the account	£2,000.00
Paid in between now and 18	£15,600.00
Growth	£7,851.61
Charges taken from the account	−£564.38
Balance at 18	£24,887.23

Why the wrapper, rather than an account in the child’s name

Nothing inside a Junior ISA is taxed. No income tax on the interest, no tax on the dividends, no capital gains tax on the growth, and nothing to declare — for the child or for you. That is worth stating plainly because a child has a personal allowance of their own and most children never come close to using it, which makes the shelter look pointless. It is not, and the reason is the next paragraph.

The parental settlement rule does not apply here. Outside a Junior ISA if income from money one parent gave one child exceeds £100 in a tax year, the whole of that income is taxed as the parent’s rather than the child’s — not just the excess. The limit applies separately to each parent and each child. It has no application to a Junior ISA at all. For the same money in a taxable account it is the rule most likely to catch a parent out.

Money from grandparents, godparents and anyone else is outside that rule anyway — it catches gifts from a parent — but it all shares the same £9,000 limit once it is inside the account. Read the limits at gov.uk — Junior Individual Savings Accounts. If that page and this one disagree, gov.uk is right and the corrections log is where to say so.

Four things this projection does not know

What they will do with it. That is the point of the panel above: at 18 it is their money, without condition. This calculator projects a balance; it cannot project a decision, and nobody paying in gets a say in it.
What £24,887.23 will buy. Every figure here is in today’s pounds with no inflation adjustment, over a term of 13 years. On a term this long that is the largest single caveat on the page — a sum that looks like a deposit today may not be one by then.
Whether the limit will still be £9,000. The allowance check uses 2026/27, applied to one year of contributions. Limits move. The projection does not check the limit in any future year, because this site has no figures for years the government has not published.
Anything about your own allowance. Nothing here touches the £20,000 you can put into your own ISAs — the two are separate limits belonging to two different people. Where yours has gone is the ISA allowance calculator, and what an adult stocks and shares ISA saves in tax is the stocks and shares ISA calculator.

The link carries the figures you typed in the address bar, so anyone you send it to sees the same result. Nothing is stored and nothing is uploaded — the CSV is built in this tab.

Worked example: £150 a month from age 8

Priya’s daughter is 8. There is £3,000 in a Junior ISA already, and Priya pays in £150 a month. She assumes 5.00% a year of growth and 0.35% a year of charges, both in today’s pounds with no inflation adjustment anywhere.

The term is not Priya’s to choose. Her daughter is 8, the account runs until 18, so the projection is 10 years — no more and no less.
£150 a month is £1,800.00 a year, against the £9,000 Junior ISA limit for 2026/27. That leaves £7,200.00 of this year’s limit — and on 6 April it is gone, because a Junior ISA allowance does not carry forward. None of it touches Priya’s own £20,000.
In 8 years her daughter turns 16 and becomes the registered contact. The account is projected to hold £21,697.22 that day. From then on Priya cannot change the investments or move the provider, and her daughter can. She still cannot take the money out.
At 18 the account matures at £27,529.54 and the money is her daughter’s to withdraw, in full, for anything at all. Of that, £3,600.00 was paid in after she was already managing the account.

Priya’s projection at the three points that matter
Point	Projected balance
Today, at 8	£3,000.00
At 16, when she takes control of the account	£21,697.22
At 18, when she can withdraw it for anything	£27,529.54
Paid in over the whole term	£18,000.00
Growth, less charges	£6,529.54

The two balances are arithmetic on the rate Priya chose, not predictions. The £9,000 limit is a published figure and the two ages are fixed by statute; what the account is actually worth on either birthday is not something anybody can tell her.

Methodology: the term, the schedule, and which half is verified

The arithmetic, in full

The term is derived, not entered. A Junior ISA runs until the child turns 18, so the projection covers 18 less their age today. That is why there is no “for how long?” box: the answer is not the reader’s to give.
The balance is a period-by-period schedule. Money goes in at the start of each period, the balance grows by the periodic rate, then the charge is taken. The annual rate is treated as an AER, so the rate entered is the rate a year compounds to rather than a twelfth of it applied twelve times, which compounds to more. The schedule is rolled up to one row a year for display and every headline figure is read back off it.
The two ages are read off the same schedule. Each year is labelled with the age the child reaches at the end of it, so the row marked 16 closes on that birthday and its closing balance is the pot on the day control passes. For a child already 16 or older there is no such row, and the answer is what the account holds today.
The allowance check is a subtraction, not a projection. Contributions for one year at the chosen frequency, measured against the £9,000 Junior ISA limit for 2026/27. Over- subscription is reported rather than clamped, because a tidy “£0 left” would hide the one thing a reader in that position has to act on.

Limits for 2026/27

Limit	Amount	Whose allowance?
Junior ISA subscription limit	£9,000.00	The child’s
Overall adult ISA subscription limit	£20,000.00	Yours, and untouched by anything on this page

Neither figure is typed into this page. Both are read from packages/tax-core/src/rules/ at build time, which is what makes the two sentences above impossible to disagree with the calculator.

Sources

Contains public sector information licensed under the Open Government Licence v3.0.

What has been verified, and what has not

The Junior ISA limit and the adult ISA limit used here were checked against gov.uk on 12 August 2026, figure by figure. That check covers the published limits only. It does not verify any result this page produces, and no named person has signed the check off yet.

The balances are a different kind of claim, and a weaker one: a fixed-rate projection is not a forecast. No rate, threshold or allowance published by government goes into them — there is nothing for a gov.uk check to be about. They are what the growth rate you entered would produce if it held exactly, every period, for the whole term. Real returns arrive as a sequence and the order changes the answer. Treat the schedule as arithmetic you can check, which is why every row of it is on the page.

What this calculator does not do

It does not adjust for inflation. Every figure is in today’s pounds. Over a term that can reach 18 years that is the largest caveat here, and it is not a conservative one.
It does not check the limit in future years. The allowance check applies one year’s published limit to one year’s contributions. This site holds no figures for tax years the government has not published, and inventing them to make a longer check possible would be the opposite of the point.
It does not know about Child Trust Funds. A child with one cannot also hold a Junior ISA until the two are combined, and a transfer between them uses no allowance. Whether that applies is a fact about the child’s date of birth and their existing accounts, not something this page can determine.
It does not calculate tax, because there is none. No income tax on the interest, no tax on the dividends, no capital gains tax on the growth, and nothing to declare. The comparison worth making is against a taxable account in the child’s name, where a parent’s gift producing more than a set amount of income a year is taxed on the parent instead — all of it, not just the excess. That limit is not held in this site’s rules files, so it is described here and deliberately not quoted.
It has no opinion. Whether a Junior ISA is the right home for this money, or whether saving in your own name and giving it later would suit your family better, is a decision this page cannot make and does not try to.

Nothing you type is transmitted or stored — there is no application server and no database. A share link is the exception: it carries your figures in the URL. What that means.

Junior ISA questions

How much can I put into a Junior ISA this year?: £9,000 in 2026/27, across a cash Junior ISA and a stocks and shares Junior ISA together — a child can hold one of each and the limit is shared between them. Anyone can pay in, so contributions from grandparents and godparents count against the same figure. The allowance is per tax year and does not carry forward: whatever is unused on 5 April cannot be used later, and a fresh £9,000 starts on 6 April.
Does a Junior ISA use up my own ISA allowance?: No. The Junior ISA limit belongs to the child and sits entirely outside your own £20,000. You can pay £9,000 into a child's account and still subscribe the full £20,000 to your own ISAs in the same tax year. gov.uk puts it plainly: parents or guardians with parental responsibility can open and manage the account, but the money belongs to the child.
What happens when the child turns 18?: The account matures and the money becomes theirs to withdraw, in full, whenever they like, for anything at all. There is no condition attached — not university, not a house deposit, not driving lessons. Nobody who paid in has any say in it, and there is no mechanism to attach one. That is the single most important fact for anyone deciding how much to put in, and it is why this calculator shows the balance at 16 as well as at 18.
Can the child take the money out before 18?: No — and this is the one place a Junior ISA is stricter than an ordinary savings account. The money is locked until the account matures, for the child as well as for you. Withdrawals before then are allowed only in narrow circumstances: terminal illness, or closing the account on death. At 16 the child takes over managing the account — choosing the investments, moving the provider — but that is control, not access.
Do I pay tax on a Junior ISA?: No. No income tax on interest, no tax on dividends, no capital gains tax on growth, and nothing for you or the child to declare, however large the account grows. The shelter matters more than it looks: outside a Junior ISA, income produced by money a parent gave a child is taxed on the parent once it passes a set amount in a year — the whole of it, not just the excess. That rule has no application to a Junior ISA at all.
Is the projection on this page a forecast?: No. It is arithmetic on the growth rate you entered: what that rate would produce if it held exactly, every period, until the account matures. Nothing published by government goes into it, nobody knows what returns will be, and real returns arrive in an order that changes the answer even when the average is the same. The Junior ISA limit beside it is a different kind of figure — that one is published, and it is checked against gov.uk.
Cash or stocks and shares?: This page projects one balance at one growth rate you choose, so it will not answer that for you and neither will any calculator — the rate is the assumption, not the output. What it can show is how much the choice of rate matters over the term you actually have, which for a young child is close to 18 years. Change the growth rate and watch the balance at maturity move. A child can hold one cash Junior ISA and one stocks and shares Junior ISA at the same time, sharing the single limit between them.
Does the money in the account count towards the allowance?: No — only new money paid in during the tax year. Growth inside the account never uses allowance, and neither does a transfer from another Junior ISA or from a Child Trust Fund. An account already worth many times the annual limit can still take a full £9,000 subscription this year.
What if I pay in more than the limit?: Tell the provider rather than waiting. HMRC identifies over-subscriptions after the tax year ends and removes the excess, so the money spends months looking sheltered when it is not. This calculator reports the excess rather than quietly capping the figure, because a tidy answer would hide the thing you need to act on.

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About the author

Sam ElleryBuilds and maintains investmentcalculator.co.uk

Sam builds and maintains the calculators on this site. Every rate, threshold and allowance behind them is checked against gov.uk before release, and the date of that check is published on each calculator and in a public log. The site exists because most UK calculators return one number and hide the working, which makes them impossible to check and easy to misread. Sam is not a financial adviser or an accountant, and nothing here is advice.

Where a calculator uses statutory figures, each one is checked against gov.uk before release and the date of that check is published on the page. The investment projections have no statutory figures — they are arithmetic on an assumption you supply. The whole of it is covered by an automated test suite, including fixtures built from HMRC’s own published worked examples. No accountant or other professional has reviewed these calculators, and no result they produce has been independently verified.

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