Junior Stocks and Shares ISA: The 18-Year Headstart
For an 18-year time horizon, choosing a cash Junior ISA is choosing to lose. The same £100 a month in equities ends up worth roughly £14,000 more by your child's 18th birthday.
£100 a month for 18 years: cash vs equities
| Wrapper | Assumed real return | Pot at age 18 |
|---|---|---|
| Cash JISA | 3% nominal (roughly flat after inflation) | ~£28,600 |
| Stocks and Shares JISA | 7% real (long-run global equity) | ~£43,050 |
| Difference | +4 percentage points a year | +£14,450 (+51%) |
Same £21,600 paid in. The wrapper choice alone moves the outcome by half a pot.
Key takeaways
For an 18-year horizon, a cash JISA is almost guaranteed to lose to inflation while equities have historically won by 5x or more in real terms.
The 2026/27 JISA allowance is £9,000 per child, shared across cash and stocks and shares versions, paid in by anyone.
£100 a month from birth at 7% real becomes roughly £43,000 by age 18, versus around £28,600 at 3% nominal in cash.
The child takes full legal control on their 18th birthday. Plan the handover conversation years in advance.