What Happens to Your Bitcoin When You Die?

According to widely-cited estimates from blockchain analytics firm Chainalysis, approximately 3.7 million Bitcoin — roughly 17 to 18 percent of all Bitcoin ever mined — is considered permanently lost. Not stolen. Not sold. Not sitting in a dormant account waiting to be claimed. Just gone. The methodology behind this figure involves identifying Bitcoin that has not moved in five or more years, adjusted for known long-term holders, but the core conclusion holds: a meaningful share of the total supply has been rendered permanently inaccessible.

No one knows exactly how much of that lost Bitcoin belonged to people who died. No rigorous study has produced a reliable figure — and anyone who gives you a precise number is making it up. But the pattern is well-documented among inheritance lawyers and estate planners who work with digital assets: early Bitcoin holders, particularly those who accumulated during the 2009 to 2013 period, died without leaving any instructions. Their families inherited the house, the car, the bank accounts. The Bitcoin sat on an old hard drive or inside a hardware wallet in a drawer, unrecognised for what it was, and eventually became inaccessible. It cannot be recovered. It cannot be inherited. It is simply gone.

Bitcoin inheritance planning is one of the most discussed and least acted-upon topics in personal finance for Bitcoin holders. The anxiety is real. The action rate is low. This chapter is here to change that.

The Real Problem: Legal Rights Don't Unlock Wallets

A bank account, a brokerage account, a pension fund — all of these have custodians. When you die, your heirs produce a death certificate and a certificate of inheritance, contact the institution, and begin the process of claiming the assets. It takes time and paperwork, but the mechanism exists. The institution cooperates, because it must.

Bitcoin in self-custody works entirely differently. There is no customer service number for the Bitcoin network. There is no forgot-password form. There is no probate court order that can compel a blockchain to release funds. The Bitcoin network does not know who you are. It does not know you are dead. It only responds to the correct cryptographic key.

If your heirs do not have your seed phrase — the 12 or 24 words that allow any compatible wallet to reconstruct your private keys from scratch — they cannot access your Bitcoin. It does not matter what your will says. It does not matter what a Swiss court orders. Without the seed phrase, the Bitcoin is mathematically inaccessible, and it will remain that way forever.

This is the fundamental problem that makes Bitcoin inheritance different from every other asset in your estate: the legal right to inherit something and the technical ability to access it are two completely separate questions. Your children may have an enforceable legal claim to your Bitcoin under Swiss law. And they may still never see it.

What Swiss Law Actually Says

Under the Swiss Civil Code, Articles 457 to 640, all assets belonging to a deceased person form part of the estate — the Nachlass. Bitcoin is property in the legal sense. It is a Vermögenswert, an asset with value, and it is included in your estate automatically, whether or not you have mentioned it in a will.

Switzerland's forced heirship rules — the Pflichtteil — mean that your children cannot be fully disinherited. Following the inheritance law reform that came into effect in January 2023, your descendants are entitled to half of their intestate share as a protected minimum. If your Bitcoin represents significant value in your estate, your children have a legal claim to a proportional share of it. A will that attempts to leave all Bitcoin to a partner or a charitable foundation can be challenged by children asserting their Pflichtteil.

But the law runs directly into the technical reality of self-custody. Swiss courts can determine that your children are entitled to a specific portion of your Bitcoin holdings. They can issue orders. They can appoint estate executors. None of it matters without the seed phrase. Swiss inheritance law is well-established. It simply has no mechanism for dealing with cryptographically locked assets. The law assumes that property can be physically transferred or legally compelled from a custodian. A Bitcoin wallet has no custodian, and a court order cannot move coins.

For Bitcoin held at a regulated Swiss exchange — Bitcoin Suisse, Swissquote, or similar — the situation is much more straightforward. The exchange is the custodian. Your heirs present a Sterbeurkunde (death certificate) and an Erbenbescheinigung (certificate of inheritance, issued by a Swiss notary or court), and the exchange cooperates with the estate process. This takes time and documentation, but it works. The exchange holds your Bitcoin on your behalf, and upon death it transfers custody to the verified heirs, just as a bank would.

Self-custodied Bitcoin — a hardware wallet, a paper wallet, or any setup where you hold your own keys — has no such mechanism. The exchange is not involved. The notary is not involved. The blockchain is indifferent.

The Four Ways Bitcoin Inheritance Fails

Understanding the failure modes is the fastest way to understand what you need to protect against.

Mode 1: Heirs don't know Bitcoin exists. This is the most common failure. The Bitcoin holder never mentioned it. It does not appear in any financial document the family sees. The family works through the estate, liquidates the obvious assets, and the hardware wallet in the study drawer is identified as a USB device of unknown purpose — or simply discarded. The Bitcoin disappears without anyone realising what was lost.

Mode 2: Heirs know Bitcoin exists but can't access it. The family knows there was Bitcoin. Perhaps the deceased mentioned it. Perhaps there is a transaction record or a hardware wallet device somewhere. But no seed phrase was left, or its location is unknown. The device requires a PIN that no one knows. After too many failed PIN attempts, some hardware wallets wipe themselves entirely. Knowing Bitcoin exists and being able to access it are entirely separate problems.

Mode 3: Hardware wallet found, seed phrase found — but a passphrase was set. This is the cruelest scenario. The heir follows instructions. They find the hardware wallet. They find the 24-word seed phrase. They enter it into the wallet recovery process. The wallet opens — and shows a zero balance. The heir assumes there is nothing there and gives up. What actually happened: the original owner had set a BIP-39 passphrase, sometimes called the 25th word, which creates a completely separate hidden wallet. The seed phrase alone opens a decoy wallet. The real funds are behind the passphrase, which was not documented anywhere. The Bitcoin is sitting there, fully intact, permanently inaccessible.

Mode 4: Exchange account found, but 2FA is on a dead phone. The heir finds login details for an exchange account. They can get to the username and password. But the account has two-factor authentication enabled — either via an authenticator app on the deceased's phone, which is now locked or wiped, or via SMS to a disconnected number. Without the 2FA backup codes, access requires a manual recovery process with the exchange that can take weeks or months of legal documentation. Most people never save their 2FA backup codes anywhere recoverable.

Each of these failures is preventable. All four require the same basic thing: someone, before they die, wrote something down and stored it somewhere accessible to the right person at the right time.

Five Solutions, From Simple to Sophisticated

The Inheritance Letter

The simplest and most important thing you can do is write a letter. Not a legal document. Not a technical manual. A plain, clear letter that tells your heirs what they need to know.

In Switzerland, a signed letter in a sealed envelope stored with a notary (Notar) or your Erbrechtsanwalt (estate lawyer) is a legitimate supplement to a will. It is not the will itself — it does not replace a formal legal document — but it provides the practical access instructions that no will ever contains. A handwritten will (holographisches Testament) is legally valid in Switzerland if it is entirely handwritten, signed, and dated. An inheritance letter of this kind can accompany it.

What the letter should contain:

• A clear statement that you hold Bitcoin and where it is held (exchange accounts and self-custody wallets)
• The type and brand of hardware wallet, and where the physical device is located
• The location of the seed phrase — not the seed phrase itself if the letter will be in the same place, but a reference to exactly where it is stored and how to retrieve it
• Whether a BIP-39 passphrase (25th word) was used, and where to find it — this is critical and frequently overlooked
• The hardware wallet PIN
• Exchange account names, the email address used to register, and username
• Where the 2FA backup codes are stored, or which device the authenticator app is on
• A contact name and phone number for someone technically capable who can assist the heir through the recovery process
• The date the letter was written, so heirs understand when the information was last updated

What the letter should not include: the seed phrase itself in plain text in an unsecured location. If the letter is stored with a notary, you may choose to include everything in one sealed envelope. If the letter has any chance of being found before your death by someone who should not have full access, store the seed phrase separately and reference its location in the letter.

The letter costs nothing and takes one hour to write. It is the single most effective action the majority of Bitcoin holders can take today.

Shamir's Secret Sharing

For holders who want more structural protection against both theft and loss, Shamir's Secret Sharing — implemented in hardware wallets as SLIP-39 — allows you to split your seed into multiple shares.

In a 3-of-5 setup, for example, the seed is divided into five shares, and any three of them together can reconstruct the original. You might store one share in a bank safe deposit box, give one to a trusted family member, give one to your lawyer, keep one in a fireproof home safe, and give one to a second trusted party. Any three of these five people or locations can recover your Bitcoin. No single person has everything — which also reduces the risk of theft while you are still alive.

This approach is supported by the Trezor Safe 5, Trezor Safe 3, and Trezor Model T hardware wallets. It is not widely available on other devices, which means it ties your setup to a specific hardware platform. It is also more complex to set up and to explain to heirs, who will need to understand that they must combine shares with other designated parties before recovery can happen. For the right holder — someone with significant holdings and access to multiple trusted parties — it is a more resilient solution than a single seed phrase document.

Multi-Signature Inheritance

Multi-signature Bitcoin custody requires multiple independent keys to authorise any transaction. In a 2-of-3 setup, three keys exist and any two are needed to spend. Used correctly, this removes the single point of failure that exists with any single seed phrase.

A practical inheritance structure: you hold one key on your hardware wallet, your Swiss notary or a trusted lawyer holds a second key in a sealed envelope, and a third key is in cold storage accessible to your heirs. While you are alive, you sign transactions with your key and the cold storage key — the lawyer's key is never used. After your death, your heirs retrieve the cold storage key, and together with the lawyer's key, they have the two signatures needed to move the funds.

Two dedicated services offer inheritance-focused multisig custody. Casa offers 3-key and 5-key vault setups starting at $21 per month, with inheritance included in all plans. Unchained Capital offers a collaborative custody model with an explicit inheritance protocol designed so that heirs can recover Bitcoin without needing to understand the technical process themselves. Both services are US-based. Swiss residents can use them — the custody itself is non-custodial and functions globally — but their estate planning attorney integrations are designed for the US legal system. If you are a Swiss resident using these services, you will need to work with a Swiss notary or estate lawyer separately to ensure the legal documentation aligns with Swiss inheritance law.

Digital Inheritance Services

Vault12 is a non-custodial mobile app that allows you to designate a guardian who holds an encrypted fragment of your wallet backup. The company does not hold your keys — the guardian, who can be a family member, lawyer, or trusted friend, holds an encrypted share. Upon death, the guardian initiates the recovery process for your heirs. The service is available to Swiss residents.

Sarcophagus is a decentralised protocol running on the BASE blockchain that functions as a dead man's switch. You encrypt a file — which might contain your seed phrase or access instructions — and set a resurrection timer. If you check in before the timer expires, it resets. If you fail to check in, the encrypted file is released to a designated recipient after the timer expires. The practical use case: if you die or become incapacitated and stop checking in, your heir eventually receives the file automatically. This runs on smart contracts, which introduces its own risks — protocol vulnerabilities, token economics uncertainty, and the requirement that your heir knows to look for and how to decrypt the message.

Both services are newer and have less track record than traditional legal instruments. Better used as an additional layer in a broader plan than a standalone solution.

Exchange Custody for Smaller Amounts

Bitcoin held at a regulated Swiss exchange — Bitcoin Suisse, Swissquote, and similar — is the simplest inheritance scenario. Your heirs follow the standard estate process: death certificate, certificate of inheritance from a notary or court, contact the exchange's estate team. The exchange cooperates. The process takes time but it works.

The trade-off is that exchange custody reintroduces counterparty risk while you are alive. You do not hold the keys. The exchange could be hacked, become insolvent, or freeze withdrawals for regulatory reasons. This chapter is not arguing that exchange custody is wrong — it is a considered choice — but that choice comes with conditions that self-custody avoids.

For smaller holdings or as a deliberate part of your inheritance plan, exchange custody is a reasonable option. For the portion of your holdings you intend to hold long-term in self-custody, the other solutions above apply.

How Much You Hold Shapes What You Should Do

The right approach depends on what you are protecting.

If your Bitcoin holdings are under CHF 10,000, the inheritance letter combined with exchange custody for at least part of your position is a proportionate and adequate approach. Write the letter, store it with your notary or in a sealed envelope in your safe with your will, and document your exchange accounts clearly.

If your holdings are between CHF 10,000 and CHF 100,000, the inheritance letter alone is the minimum — but supplementing it with Shamir's Secret Sharing on a Trezor or a basic multisig setup adds meaningful protection both against loss and theft.

If your holdings exceed CHF 100,000, the professional multisig services — Casa or Unchained — with formal legal integration through a Swiss estate lawyer are worth the cost. At this level, the annual cost of professional custody is negligible relative to the value being protected, and the legal clarity around inheritance becomes more important.

These are frameworks, not financial advice. Your specific situation — family structure, technical ability of heirs, number of wallets and exchange accounts — will shape the right answer.

What to Do This Week

Write the letter.

Not next month. Not when you have time to research the perfect solution. This week, take one hour and write a clear document that tells your heirs what they need to know. Where is the Bitcoin? Where is the hardware wallet? Where is the seed phrase? Is there a passphrase? What exchange accounts exist? Where are the 2FA backup codes?

A rough draft in a sealed envelope in your safe, given today, is infinitely more useful to your family than a perfect plan that never gets written. The detailed solutions — Shamir shares, multisig custody, digital services — can follow. The letter comes first.

Put the date on it. Review it once a year, or any time something changes — a new wallet, a new exchange account, a change in hardware. The goal is not a perfect document. The goal is a document that exists.

If you are in Switzerland and you have a notary who handles your estate documents, ask about depositing a sealed envelope with your will or alongside it. This is a standard practice and costs very little. Your heirs will not be asking a blockchain for your Bitcoin. They will be asking you — through what you left behind.

This chapter is general information, not legal advice. Swiss inheritance law is specific to your circumstances, and anyone with significant Bitcoin holdings should consult an Erbrechtsanwalt (estate lawyer) familiar with digital assets.

Chapter Summary

• An estimated 3.7 million Bitcoin is considered permanently lost, according to widely-cited Chainalysis estimates — a meaningful share attributable to holders who died without leaving access instructions. It cannot be recovered.

• Swiss law treats Bitcoin as an estate asset under the Civil Code. Forced heirship rules (Pflichtteil) apply to children. But legal entitlement is worthless without the seed phrase — no court order can unlock a self-custodied wallet.

• The four failure modes are preventable: heirs not knowing Bitcoin exists, knowing it exists but lacking access, finding a seed phrase that opens only a decoy wallet due to an undocumented passphrase, and being locked out of an exchange by 2FA on a dead phone.

• The inheritance letter — a clear document stored with a notary, lawyer, or in a fireproof safe alongside your will — is the single most effective action most Bitcoin holders can take. Write it this week.

• More advanced solutions — Shamir's Secret Sharing (SLIP-39), multisig custody via Casa or Unchained, and digital services like Vault12 — offer greater resilience for larger holdings. The right solution depends on how much you hold.