The appeal is obvious: a small amount now, a meaningful amount at eighteen, and a lesson in patience attached to it. The mechanics are less obvious, because a child cannot safely hold keys and a gift you keep holding is not really a gift.
Decide what you are actually doing
Three quite different things get called "giving bitcoin to a child":
Holding it for them. It stays in your wallet, mentally earmarked. Simplest, and the least real - it is part of your estate, exposed to your circumstances, and depends entirely on you following through.
Giving it to them now, held by a parent. A genuine transfer into a wallet a parent controls on their behalf. Real, but its survival depends on that parent's key management for the next fifteen years.
Giving it to them on a fixed future date. The transfer is set up now, delivery happens at the date, and nobody has to do anything in between.
Which you want depends mostly on how much you trust the intervening years - and honestly, on how much you trust yourself not to spend it.
The custody problem
A nine-year-old cannot look after a seed phrase, and a fifteen-year-old absolutely should not have access to a five-figure sum during a bull market. But keeping the keys yourself for a decade means the gift depends on your continued attention, your health, and your own backup discipline.
The common solutions:
- A dedicated hardware wallet per child, held by you, with the seed phrase stored with your inheritance documents and handed over at the agreed age. Cheap and clean, and it fails if you lose the backup or forget.
- A custodial account in a parent's name. Easy, but it is an exchange balance with all that implies, and it is trivially spendable in a crisis.
- A timelocked transfer to an address the child will control. Delivery is automatic. The hard part moves to the front: you need an address that will still be theirs in ten years, which usually means a wallet set up now and its backup stored by a parent.
Tax, briefly and non-authoritatively
Rules differ enormously by country and none of this is advice - check with someone qualified where you live.
The general shape: in many jurisdictions giving away an appreciated asset is itself a taxable event for the giver, gifts to children may fall under annual allowances, and the recipient inherits some cost basis that determines what they owe when they eventually sell. In the UK, capital gains on disposal and the seven-year inheritance tax rule are the usual concerns; in the US, the annual gift tax exclusion and carryover basis. Getting this checked before you transfer a large amount is much cheaper than fixing it afterwards.
Keep a record of the date and the value on that date. Future-you will need it and will not remember.
What a timelocked gift looks like
You set the recipient address and the date at the start. The coins move to an address whose script the Bitcoin network refuses to unlock until then - not by policy, but because nodes reject an early spend as invalid. On the date, it delivers.
The appeal for a gift specifically:
- It cannot be quietly reabsorbed if your circumstances change. That is either the point or a serious drawback, depending on your circumstances.
- A teenager cannot access it early no matter how persuasive they become.
- It happens without anyone remembering - including you.
Everything is fixed at setup and nothing can be corrected. Wrong address, wrong date, or a wallet whose backup is lost by the time it arrives: all unrecoverable. Set the recipient wallet up first, verify a small test transaction reaches it and can be spent from it, and only then set up the lock.
Also think about the date itself. Exactly eighteen is traditional and is also the age at which a lump sum is least likely to be handled well. Twenty-one, or splitting it across two dates, tends to age better.
If we are holding it
With VaultUntil the lock itself is enforced by Bitcoin and nobody can break it early. At the unlock date, our key signs the delivery - so a gift set fifteen years out is a fifteen-year bet that we are still here to sign it. The risk page puts it bluntly, and for a long horizon you should weigh it seriously, or hold the timelock key yourself using the script directly.