Junior ISAs: Investing for Your Children Properly

Whatever your own portfolio looks like, your child holds the one asset money cannot buy: an eighteen-year head start. Money invested at birth compounds through two full doublings before adulthood — the Junior ISA is the wrapper built to capture that, tax-free.

How JISAs work

A parent or guardian opens the account; anyone — parents, grandparents, family friends — can pay in, up to £9,000 per tax year (separate from your own £20,000 allowance). Cash and stocks & shares versions exist, a child can hold one of each, and all growth is tax-free. The money is locked until the child turns 18 — no early access for anyone, including you — at which point it converts to an adult ISA and becomes theirs outright.

Equities, almost always

Nowhere is the time-horizon rule clearer: a newborn's JISA has an 18-year horizon, comfortably beyond the five-year equity threshold, yet the majority of JISA money nationally sits in cash — meaning most families are choosing near-certain real-terms erosion over probable growth for the longest-horizon money they will ever control. A global index fund (explained here) inside a stocks & shares JISA is the boring, correct default; a glide toward cash in the final couple of years is reasonable if the money has a known age-18 purpose.

The numbers that make relatives generous: £50 a month from birth at illustrative long-run equity returns reaches roughly £19,000–£20,000 by 18 — from £10,800 contributed. £9,000 lump sums from a grandparent early on can plausibly double twice. Grandparents note: contributions are gifts for inheritance tax purposes, usually covered by the annual exemptions or surplus-income rules.

The age-18 catch

At 18 the money is legally theirs — for university, a house deposit, or a very good festival summer. You get no say. Two mitigations: first, financial education is part of the gift — a teenager who has watched "their" fund fall 20% and recover owns an education most adults lack; second, if genuine control matters to you (larger sums, complicated family situations), a JISA may be the wrong vehicle — money kept in your ISA earmarked for them stays under your control and can be gifted when you judge right, at the cost of using your own allowance and losing the JISA's separateness.

Priorities and practicalities

Fund your own emergency fund, pension match and ISA before the children's — the airline-oxygen-mask rule of family finance; an 18-year-old with solvent parents beats one with a JISA and struggling ones. Check fees with the usual scrutiny — percentage-fee platforms suit small growing pots. If your child has an old Child Trust Fund (born 2002–2011), transfer it into a JISA; CTFs are a graveyard of forgotten, fee-heavy accounts. And set contributions as a standing order — the same automation logic as every other good investing habit.

This is general education, not personalised financial advice. Investing involves risk, including the risk of losing money, and past performance is not a guide to future returns. Nothing here recommends any specific investment — for anything genuinely complex or high-stakes, speak to a regulated financial adviser.