Future Builder Calculator

See how much your child's investments could grow to by age 18

Free calculator for Junior ISAs and Junior SIPPs with tax relief projections

Your child could have

£15,354

by age 18

Including £3,071 from government tax relief!

Account type:

Frequency:

Child's age:10 years

Monthly contribution:£100

£10£240

Your Contributions

£9,600

Over 8 years

Investment Growth

£3,354

From 6% annual return

Tax Relief Growth

£3,071

From £2,400 government bonus

Growth Projection

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Interested in Junior SIPPs? See the Lifetime Value!

This calculator shows what your child could have by age 18. But with a Junior SIPP, the government's 25% tax relief bonus keeps growing for 50+ more years until retirement. Our Tax Relief Calculator shows what that free money could become - often £100,000+!

Calculate Lifetime Tax Relief Value

How the Calculator Works

Compound Growth

The calculator uses 6% annual growth (typical for diversified index funds) compounded monthly over time.

Tax Relief (SIPPs)

Junior SIPPs get 25% tax relief from the government (e.g., £2,880 contribution → £3,600 total).

Tax-Free Growth

Both Junior ISAs and SIPPs grow tax-free - no income tax or capital gains tax on investment returns.

Frequently Asked Questions

Is 6% a realistic growth rate?

Yes, 6% is a conservative estimate for a diversified global index fund over 10+ years. Historical returns for the FTSE Global All Cap Index average around 8-10% annually, but we use 6% to be conservative.

What's the difference between Junior ISA and Junior SIPP?

Junior ISAs are tax-free savings accounts accessible at age 18, with a £9,000/year limit. Junior SIPPs are children's pensions with 25% tax relief but accessible only at age 57+, with a £2,880/year contribution limit (£3,600 with tax relief). Read our full comparison.

Can I have both a Junior ISA and Junior SIPP?

Yes! Many parents use both - a Junior SIPP for long-term retirement savings (with tax relief) and a Junior ISA for shorter-term goals accessible at 18.

How is tax relief calculated for Junior SIPPs?

The government adds 25% (basic rate tax relief) to contributions. For example, if you contribute £240/month (£2,880/year), the government adds £720/year, making the total £3,600. This bonus also grows over time. Learn more about tax relief.