How does a testamentary trust for a young child work?

Yes, this is commonly done through a testamentary trust within your will. Instead of leaving assets directly and outright, your will can direct that your assets be held on trust for your children, with the trustees managing the funds for their benefit, for example, paying for education and living costs, until they reach an age you specify, such as 21 or 25, or in stages. Under the Trusts Act 2019, trustees have duties to act honestly, in good faith and for the benefit of the beneficiaries, and to keep proper records. You should choose reliable, capable trustees and consider appointing more than one, and clearly set out the powers and any guidance for the trustees in the will. Discuss the structure with a lawyer to make sure it reflects your wishes and provides adequate flexibility for changing circumstances.