Bitcoin's defining property is that only the keyholder can move it. That is exactly what makes it good money and exactly what makes it disastrous to inherit. There is no death certificate you can present, no branch to visit, no process at all. If your family cannot reconstruct your keys, the coins sit visible on the blockchain forever and nobody can touch them.
An unknown but large quantity of bitcoin is already in this state.
The two failures
Almost every lost inheritance is one of these:
Nobody knew it existed. The estate gets settled, the house gets cleared, a nondescript USB device goes in a skip. No amount of key management helps here - the problem is purely that the information never left your head.
They knew, but could not access it. A seed phrase in a safe nobody has the combination to. A passphrase you never wrote down. Instructions that assume knowledge your family does not have. "It's in the bitcoin wallet" means nothing to someone who has never seen one.
Start with the letter
Before any clever cryptography, write a document. Plain language, no jargon, addressed to someone who has never used bitcoin:
- That bitcoin exists, roughly how much, and that it has real value.
- Where the device is. Where the backup is. Physically, specifically.
- What the words on the metal plate are for, and a warning never to type them into a website or send them to anyone claiming to help.
- Who to ask. Name an actual person who understands this, and ask them first.
- Explicitly: "anyone who contacts you offering to recover this is stealing it." Bereaved families are targeted, and the scripts are good.
Keep this separate from the seed phrase itself. The letter says where things are; it is not itself the key. Then tell someone the letter exists. A perfect document nobody finds is the first failure again.
The lawyer problem
Your will is a public document in many jurisdictions once probate begins. Never put a seed phrase in it. Never put one in anything a solicitor's office photocopies or emails.
What a will can do is name who inherits the bitcoin and point at the existence of instructions held elsewhere. What it cannot safely do is contain the keys. Most solicitors have no working model of this and will cheerfully suggest otherwise.
The options, ranked
A letter plus a hardware wallet - the baseline. Cheap, works, depends on your family finding and understanding the letter. Good enough for most people. Pair it with the cold storage guide.
Multisig with a key held by someone else - 2-of-3 where you hold two keys and a trusted person or a collaborative-custody service holds the third. No single point of failure, survives your death cleanly, and the coins cannot be moved by that third party alone. The right answer for large amounts. It is also real work to set up and your heirs need a plan they can follow.
A collaborative custody service - companies exist that hold one key in a multisig and have a documented inheritance process. You pay for it, and you accept them as a dependency.
A timelocked transfer - coins locked to a date and a recipient address fixed at the outset. It delivers whether or not anyone remembers, which is its whole appeal: it does not depend on your family understanding bitcoin, finding a device, or reading a letter. On the date, it arrives.
Timelocks are a narrow tool for this. The date is fixed at setup and cannot be changed, so you are guessing at a year. Set it too early and you have given away money while you are alive; too late and your heirs wait. It works best as a supplement - a portion arriving at a known date, alongside a proper plan for the rest - rather than as the whole estate.
If you use a service
Any hosted arrangement, ours included, adds a dependency on a company still existing decades from now. Read what you are trusting: with VaultUntil the network stops the coins moving early, but at unlock our key signs the payout, so a twenty-year lock is a twenty-year bet on us. The risk page states it plainly, and for an inheritance horizon it deserves more weight than it does for a two-year lock.
Do this part regardless
Whatever route you choose, once a year: check the backup is where you think, confirm the named person still knows, and update the letter if anything moved. An inheritance plan written once and never revisited describes a wallet you no longer use.