The Junior ISA was introduced in 2011 and has quietly become one of the UK's most powerful long-term wrappers. The £9,000 annual limit (HMRC, 2025/26) - combined with 18+ years of compounding - has produced some surprisingly large pots.

Key takeaways

  • Junior ISA annual subscription is £9,000 for 2025/26 (HMRC).
  • JISAs are accessible by the child at 18.
  • Funds inside grow free of UK income tax and CGT.
  • Long horizons amplify the compounding effect.
  • Junior SIPPs offer an even longer wrapper but lock until pension age.

How the maths works

£9,000 per year for 18 years at a hypothetical 7% real return compounds well into six figures. Actual returns vary.

What investors typically hold

Many JISAs hold global tracker funds. Single-stock JISAs are higher risk and not suited for most families.

When the child takes control

At 18 the account converts to an adult ISA. Parents can guide but not legally restrict use after that date.

What this means for UK investors

A fully-funded JISA can build a meaningful pot by adulthood. Even partial funding from grandparents or relatives can transform a child's financial start.

Risks to watch

  • Children may withdraw at 18 for non-Investment uses.
  • Concentration in single themes or funds.
  • High fees compounding for 18+ years.
  • Future rule changes to JISA limits or access age.