If you have children under 18 and you're writing a will, appointing a guardian is one of the most consequential decisions in the document. It's also one of the most over-thought - which is why a lot of parents put off writing the will at all.
This article walks through what a guardian is, how the appointment works in UK law, what to look for in your choice, and how to have the conversation.
What a testamentary guardian actually does
A testamentary guardian is a person appointed in your will to take parental responsibility for your children if both parents die before the children turn 18.
That includes:
- Where the children live.
- Their schooling and major decisions.
- Their day-to-day care, or arranging that care.
- Most things a parent does, until the children are 18.
Crucially, a guardian doesn't automatically get control of the children's money. The financial side is handled separately by the will's executors and any trustees - so a great carer can guardian your kids without being a financial whiz, and vice versa.
When the appointment kicks in
The standard rule: a testamentary guardianship appointment in your will only takes effect when both parents with parental responsibility have died. If one parent dies, the surviving parent continues to have parental responsibility - and your appointment of a guardian is held in reserve, only kicking in when the second parent dies.
There are exceptions:
- If only one parent has parental responsibility (an unmarried father not named on the birth certificate, in a few situations), the guardian appointment of that parent can take effect immediately on their death.
- A residence order or child arrangements order in favour of the deceased parent can also bring the appointment forward.
For most families this means: appointing a guardian is "in case the worst happens to both of us at once".
Who can you appoint?
Anyone of legal age and capacity. Common choices:
- A sibling.
- Close friends.
- Grandparents (with the caveat that they may not outlive you - a substitute is essential).
- A combination - co-guardians.
You can appoint two guardians together (joint guardianship). They have to agree on decisions; if they disagree the courts can be asked to resolve. Joint guardianship can be a brother and sister of the deceased parent acting together, or a married couple. It's a real check on power, and it's also a real ongoing complication if the relationship ever breaks down.
What to look for in a guardian
A useful framework:
- Existing relationship with your children - they already know and trust this person.
- Willingness - it's a 10-15 year commitment, not a small ask.
- Stage of life - someone whose own children are similar ages can absorb yours into existing routines; someone with adult children can enjoy parenting again. Consider matches and mismatches.
- Geography - a guardian who lives 4 hours away will mean uprooting school and friends. Consider whether that's acceptable.
- Values - religious, political, lifestyle. Your kids will absorb whoever's values they live with.
- Stability - financial, marital, lifestyle.
- Health and life expectancy - grandparents are often the first instinct but unlikely to outlive a 25-year guardianship. Better as a substitute.
The right answer for most families is a sibling or close friend in the same generation, with a grandparent or another sibling as substitute. The appointment is just an instruction; nothing stops the family choosing differently together if circumstances are different at the time.
Naming a substitute
Always. Your first-choice guardian can predecease you, lose capacity, or simply turn the role down when the time comes. A will that says "I appoint X" with no fallback creates a court application if X can't act.
A typical structure:
> I appoint X and Y jointly to be guardians of any of my children under 18. If either or both of them is unable or unwilling to act, I appoint Z as substitute guardian.
The conversation
This is the bit most parents dread. There's no magic phrasing, but a few things help:
- Pick a calm moment - not a family event.
- Be specific that it's a will-writing decision, so they understand it's hypothetical and you're not dying.
- Tell them why you're asking them - the things you specifically value about how they'd parent.
- Give them time to think and a real path to say no.
- Talk through finances - what would the financial arrangement be, and from what fund.
- Re-confirm every few years.
Most people are honoured. Some say no for very valid reasons (their own family situation, health, age). Both responses are useful information.
What if I don't appoint anyone?
If both parents die without appointing a guardian, the family courts decide. Anyone can apply - relatives, friends, social services. The court chooses based on the child's best interests.
This typically means:
- A delay during which a temporary placement is decided.
- A potentially adversarial process if multiple relatives apply.
- A choice that may not match what the parents would have wanted.
A guardian appointment in a will sidesteps all of this and gives the courts a strong steer. The court can override an appointment in extreme cases (e.g. evidence the appointed guardian is unsuitable) but that's rare; the parents' choice carries significant weight.
For complex estates, we recommend you seek assistance from a Trusted Hands Advisor or your own legal advice.
The financial side
Guardians look after the children. Trustees (often the executors) look after the children's money. A typical setup:
- The estate is held on trust until the children reach 18 (or 21, or 25 - your call).
- Trustees can use income and capital for the children's maintenance, education and benefit during the trust period.
- The guardian can request funds from the trustees as needed.
- At the chosen age, capital is distributed.
Two issues to think about:
- Should the guardian and trustee be the same person? It's simpler but it removes a check on spending. Different people = more bureaucracy but more accountability.
- Should there be a "Bare trust" or a "discretionary trust"? Bare trusts are simpler but inflexible (the child has an absolute right at 18). Discretionary trusts are more flexible but have ongoing tax and administrative costs.
Our cohabiting and blended families guides get into more of the trust structures.
> Ready to start your will? Trusted Hands turns these decisions into a 15-30 minute guided builder. Start free → — only pay when you download.
Frequently asked questions
Can grandparents be guardians?
Yes, but consider age and life expectancy. Grandparents are often appointed as substitutes rather than primary - the appointment lasts up to 18 years and many grandparents won't be around for that.
What if the other parent and I appoint different guardians?
The general rule is that the appointment of the parent who dies last takes effect. So if you and your partner appoint different guardians and you both die in the same accident, the position can be unclear. The simplest answer is to appoint the same guardian in both wills, ideally jointly.
Can a guardianship appointment be challenged?
Anyone with sufficient interest can apply to the court to discharge or vary an appointment. The court weighs the welfare of the child against the appointed guardian's circumstances. Strong grounds are needed - the parents' choice carries significant weight unless the guardian is plainly unsuitable.
Does the guardian have to live in the UK?
No. A guardian abroad is legally valid, though it raises practical questions - the children's habitual residence, immigration, schooling. If your first-choice guardian lives overseas, consider a UK-based substitute who can manage things in the immediate term.
What if my children are over 18 by the time I die?
The guardianship appointment lapses naturally. There's no harm in leaving it in the will - if all the children are 18+ at your death, the appointment simply has no effect.
Does the guardian have any say in the will money?
Only what the will gives them. The trustees control the funds; the guardian can request funds for the children's needs but doesn't directly receive money for themselves unless the will provides for it (e.g. a small lump sum to cover initial costs of the children moving in).
Naming guardians is one of the strongest reasons to write a will if you have young children. Start yours online - the Trusted Hands engine prompts you for guardians and substitutes when there are minor children in the picture.
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