A JISA for My Son, and the Pot He Won't Know About

Why I'm Writing This

I opened my first ever stocks and shares account this week. It wasn't for me. It was a Junior ISA for my son, Otto.

This is a slightly different kind of post for Scenarios, because it's mine, in the first person, rather than the more neutral pieces we usually publish. But the decisions I'm making for Otto turned out to be a useful prompt for a piece on how a JISA actually works, what it doesn't do, and how it might be used as more than just a tax-efficient pot.

What a JISA Is, In Sixty Seconds

A Junior ISA is a tax-free account for under-18s. Two flavours: a Junior Cash ISA and a Junior Stocks and Shares ISA. The annual allowance is currently £9,000, and it can be split across both.

The account is opened by a parent or guardian, but the money belongs to the child from day one. No income tax on the returns. No capital gains tax. No tax to pay when it converts to an adult ISA at 18.

From age 16 the child can manage the account themselves. They still can't withdraw until they turn 18. On their eighteenth birthday the JISA automatically becomes an adult ISA and the money is theirs to do whatever they like with.

That last sentence is the one that did the most work in my own thinking.

The Thing the Brochures Don't Say

A £9,000 allowance from birth, fully used and invested at a long-run real return of 5% a year, would compound to somewhere in the region of £250,000 by Otto's eighteenth birthday. Even at half that contribution rate, it's a six-figure handover.

That's a lot of optionality. It's also a lot of money to hand to an eighteen-year-old with no warning, no context, and no ability for me to override the timing if he isn't ready for it. The JISA mechanics give him the keys at 18, full stop. Not 21. Not "when you finish university." Not "when you've got a deposit lined up." Eighteen.

I think most parents who look at a JISA properly arrive at the same uneasy realisation. The tax wrapper is generous because the strings are short.

My Solution: Two Pots, Two Jobs

Rather than try to solve that dilemma inside the JISA, I'm splitting it.

Pot 1 is the JISA, in Otto's name. It's the formal, tax-advantaged account. He'll have access to it at 18.

Pot 2 is a separate account in my own name, earmarked for him but legally mine. It pays the cost of being in my name (no tax wrapper, returns will be taxed under my allowances) in exchange for one thing: I get to decide when he sees it. Maybe that's at 21. Maybe at 25. Maybe it's a deposit on a first house. Maybe it's split across milestones. The point is that the decision lives with me, not with the calendar.

The two pots aren't trying to do the same thing. The JISA does the tax-efficient compounding. The side pot does the timing.

If anything goes catastrophically wrong with how he turns out as an eighteen-year-old, the JISA money is his to make whatever mistakes he wants with. The side pot is still there, intact, for a later version of him.

Using the JISA as a Classroom

Once I'd separated the two jobs, the JISA stopped having to be the optimal long-term portfolio. It can do something more useful than that. It can teach him.

The plan is to let Otto pick what goes into the JISA, within sensible limits. The brands he knows. The companies whose products show up in his life. McDonald's, Disney, Apple, Nike, whatever he's into when he's old enough to care.

The financial outcome of this is almost beside the point. The side pot is doing the heavy lifting. The JISA is the part of the system designed to make ownership feel real.

There's a practical reason this approach works. I opened the JISA with Hargreaves Lansdown, which charges no dealing fees and no account charges on its Junior ISA product. That matters more than it sounds. Standard share-dealing fees on an adult account run around £10 a trade, and on a small JISA built up gradually that figure would eat the educational element alive. Every "let's buy a share of Disney" would cost a meaningful chunk of the share itself. Free dealing is what makes letting a child pick individual companies, in small amounts, economically sensible.

Consumer, Employee, Shareholder

There's a specific lesson I want him to get from this, and McDonald's is the easiest way to explain it.

Most people, when they think about a company like McDonald's, encounter it in exactly one way: as a customer. You hand over money, you get food, the relationship ends a few minutes later.

But there are three positions you can occupy in relation to the same company:

• The consumer buys the burger. The transaction takes a few minutes. The money leaves your pocket and the experience is over.
• The employee is paid to be there. They've traded their time for an agreed wage. The relationship is structured, capped, and ends when the shift does.
• The shareholder owns a slice of the business. Every burger sold anywhere in the world contributes, in a microscopic way, to the value of what they own. They don't trade time for it. They don't trade money each visit. They hold the slice, and the business does the work.

Almost no one is taught this distinction explicitly. We pick it up by accident, late, often after we've already chosen which side of the counter we'll spend the next thirty years on. I'd like Otto to know it earlier, in his bones, by actually owning a tiny piece of something he already interacts with.

What This Post Isn't

A few things to be clear about. None of this is financial advice. Scenarios isn't an FCA-authorised firm and I'm not a financial adviser. Decisions about how to structure money for a child, especially across tax wrappers and informal arrangements, involve a lot of moving parts (inheritance considerations, your own tax position, your other long-term goals) and the right answer for one family won't be the right answer for another. If you're trying to work out the structure that fits your circumstances, that's exactly the conversation a regulated adviser is paid to have with you.

What I can do is share the framing, because the framing is the part I almost missed when I opened the account.

Where Scenarios Fits, and Where It Doesn't

To be honest about the tool I work on: Scenarios doesn't model JISAs directly. A JISA sits in the child's name rather than yours, and the platform is built around your own long-term plan, not someone else's.

What it can model is the side pot, because that pot sits in my name. It's part of my own financial picture, alongside the pension, the ISA, and projected income in retirement. Earmarking a slice of my own money for Otto's twenty-fifth birthday is, from Scenarios' point of view, just another contribution sitting inside my plan.

The release of that money to him is also handled. Scenarios lets you plan life events and gifting inside the simulation, which means I can stress-test how affordable a particular gift actually is: £10,000 towards a wedding, £30,000 towards a house deposit, a phased handover across several birthdays. The model shows me both sides: what putting the money aside costs me along the way, and what the rest of my plan looks like once that lump sum has left it.

The honest version of the modelling exercise is this: Scenarios shows me what trading off contributions to my own retirement against the side pot for Otto actually costs in both directions. That's a trade-off I find genuinely hard to think about without a tool.

If you want to do the same kind of analysis for your own plan, you can start a free plan.

Further Reading

• HMRC. Junior ISA: rules, limits, and tax treatment.
• Money and Pensions Service. Talking to children about money at different ages.
• Lieber, R. (2015). The Opposite of Spoiled. HarperCollins.