Junior SIPP calculator

See how contributions to a Junior SIPP grow over time, with the automatic 20% tax top-up every contribution gets even though the child has no income of their own.

Figures for the 2026/27 tax year. Last reviewed 28-09-2026.

How tax relief works for a child with no income

A Junior SIPP is a pension opened in a child's name, usually by a parent or grandparent, and run by them until the child turns 18. What surprises a lot of people is that HMRC still adds 20% tax relief to contributions, even though the child has no earnings, no tax bill, and won't for years.

This isn't the same relief mechanism as an adult's pension. For an adult, relief at source assumes you're a basic-rate taxpayer and tops up accordingly, with higher and additional-rate taxpayers able to reclaim more through self-assessment. A non-earner's relief is fixed at exactly 20%, regardless of who's actually paying the money in — a higher-rate-taxpayer grandparent gets exactly the same 20% top-up as anyone else, because the relief is based on the child having no tax liability to offset it against, not on the contributor's own tax position.

Pay in £80 and HMRC adds £20, making a £100 gross contribution — the same 80/20 split as a basic-rate adult's relief-at-source pension, just without any way to claim more.

A worked example

Say a parent pays £100 a month into a Junior SIPP from when their child is 2, aiming to keep it invested right through to a retirement age of 65 rather than stopping at 18. That's £1,200 a year net, grossed up to £1,500 a year with relief — £1,200 from the parent, £300 from HMRC, comfortably under the £3,600 gross annual limit.

With a 5% growth assumption, typical charges, and inflation running at 2.5%, that £1,500 a year compounding for 63 years builds into a substantial sum by retirement age, even though the contributions themselves stop the moment the parent decides to stop paying in (there's nothing stopping the child, once grown, from carrying on contributing themselves).

The chart below breaks the pot into three parts: what was actually paid in, the 20% relief added automatically, and the investment growth on top. Over a horizon that long, growth typically ends up dwarfing both the contributions and the relief combined — which is exactly the case for starting a pension as early as possible.

The £3,600 gross annual limit

A non-earner can have up to £3,600 gross paid into their pension each tax year and still get the 20% top-up — that's £2,880 actually paid in, plus £720 of relief. Try to pay in more than that in a single tax year, and only the first £3,600 gross gets the relief; anything beyond that either isn't accepted by the scheme or doesn't attract any top-up, depending on the provider.

This calculator caps the gross contribution at that limit automatically and tells you if your monthly or annual figure implies going over it, so you can see straight away whether your planned contribution fits within the limit.

Age 18, and what happens after

At 18, legal control of the Junior SIPP passes from whoever was managing it to the child themselves — the money stays invested and locked away under normal pension rules, it's simply no longer the parent's account to run. Nobody, including the now-adult child, can access it until normal minimum pension age, which is 55 today and legislated to rise to 57 from 2028.

Choosing 'continue to retirement' in this calculator simply extends the projection horizon beyond 18, on the assumption that contributions (from whoever is paying them by then) keep going at the same rate. It isn't a claim that the parent will still be the one paying at that point — just a way to see the long-run effect of starting early, which is usually the single biggest driver of the final figure in a pension projection this long.

Common mistakes and misunderstandings

The most common one is assuming the relief depends on the contributor's own tax rate, the way it would for their own pension. It doesn't — a basic-rate, higher-rate or non-taxpaying contributor all get exactly the same 20% added to a child's pension, because the relief is based on the child's position, not theirs.

The second is not realising the £3,600 gross limit is shared across everyone contributing to that child's pension in a tax year, not a separate £3,600 per contributor. If two grandparents and a parent are all paying in, their combined contributions are what's capped, not each of their individual amounts.

The third is underestimating how much starting early matters over a horizon this long. A relatively modest monthly amount started at age 2 and left compounding to a normal retirement age can end up contributing more from growth than from everything anyone ever paid in — which is the whole point of the chart below.

Frequently asked questions

Does the 20% relief depend on my own tax rate as the contributor?

No. The relief on a non-earner's pension contribution — including a child's Junior SIPP — is always 20%, regardless of whether the person paying in is a basic-rate, higher-rate or non-taxpayer. It's based on the child having no tax liability to offset the relief against, not on the contributor's own marginal rate.

What's the maximum I can pay into a Junior SIPP each year?

£2,880 net (£3,600 gross once relief is added) per tax year, shared across everyone contributing to that child's pension — not £2,880 per contributor. Pay in more and the excess either isn't accepted or doesn't get the 20% top-up, depending on the provider's rules.

Who controls a Junior SIPP, and when does that change?

A parent or legal guardian opens and manages a Junior SIPP for a child under 18. At 18, control transfers to the child, though the money remains a pension and stays locked away under normal access rules — turning 18 doesn't give them access to withdraw it.

When can the money actually be accessed?

Not until normal minimum pension age, which is 55 today and is legislated to rise to 57 from 6 April 2028. A pension started for a young child will almost certainly see further rises to this age before they're anywhere near retirement.

Is a Junior SIPP better than a Junior ISA for a child?

They do different jobs. A Junior ISA is accessible to the child at 18 and can be used for anything; a Junior SIPP is locked away for decades but gets tax relief added on top of every contribution. This calculator only models the Junior SIPP side — it isn't a comparison tool between the two.

Does the child's own future earnings affect this pension?

Once the child starts earning, they can contribute in their own right too, subject to the normal earnings-based annual allowance rather than the £3,600 non-earner limit. This calculator only models contributions up to the point and rate you've set — it doesn't attempt to project the child's own future earning or contributing behaviour.