Can a child or teenager invest in a halal ETF or managed fund?

Not directly in most cases - a minor generally cannot hold the investment in their own name, so an adult, trust or custodial arrangement is used.

The common approaches are an account held by a parent as trustee for the child, a formal trust, or a broker's minor account. Whichever is used, two things need attention:

• Beneficial ownership - who the ATO treats as owning the income matters, and it is not always the name on the account
• Minors' tax rates - penalty rates apply to unearned income of minors above a low threshold, which can make a poorly structured account expensive

Check the broker's and the fund's own rules, and take the tax question to a registered tax agent.