Bitcoin inheritance: organising the succession

Bitcoin raises a transmission problem of a new kind. The seed phrase×Seed phraseSequence of 12 or 24 words (usually in English) that encodes your master key. Universal wallet backup : with these words, you can restore your funds on any compatible software.See in the lexicon → is enough to move the entire holding, but without it bitcoins become inaccessible forever. No third-party service can reset a self-custody×Self-custodyModel in which you hold your own private keys. Your bitcoins depend on no third party. This is Bitcoin's founding promise.See in the lexicon → wallet×WalletSoftware or device that manages your Bitcoin keys and lets you sign transactions. A wallet does not really « hold » your bitcoins, it holds the keys that prove you own them.See in the lexicon → the way one would ask for a new bank password.

Inheritance planning becomes a competence in its own right for the bitcoiner×BitcoinerPerson interested in Bitcoin, who holds some and adheres more or less to its values (individual sovereignty, sound money, decentralisation).See in the lexicon →. It combines three complementary plans : a legal layer (will, protective mandate), a technical layer (seed backup, multisig×Multisig (multi-signature)Configuration where a transaction must be signed by several independent keys to be valid (for example 2 of 3). Reduces the risk that a single key theft causes loss of funds.See in the lexicon → with family co-signers, time-locks), and a documentary layer (clear instructions for heirs, without revealing the secrets prematurely).

This article reviews the handwritten will versus the notarised will in French and Swiss law, the 2-of-3 or 3-of-5 multisig architectures dedicated to inheritance, services such as Casa Inheritance or Unchained Trusts, and the pitfalls to avoid (revealing the seed inside the will, forgetting the BIP39×BIP39Standard defining the list of 2,048 words used for seed phrases. Lets every wallet brand generate seeds that are compatible with each other.See in the lexicon → passphrase×PassphraseExtra word or phrase you add to your seed phrase to create a hidden wallet. Optional security layer, independent of the seed.See in the lexicon →).

The testament: holographic vs notarial

Without a testament, your bitcoins follow intestate succession: your country's civil law decides who inherits and in what proportions. For Bitcoin, this is almost always insufficient: legal heirs may ignore the existence of the bitcoins, or not know how to access them. A testament lets you explicitly designate who receives what, and attach technical instructions.

Two main forms coexist in most relevant jurisdictions.

• Holographic testament. Written entirely by hand, dated and signed by the testator. Free, freely modifiable, requires no outside intervention. Recognised in CH (art. 505 CC), FR (art. 970 Code civil), DE (eigenhändiges Testament, §2247 BGB), IT (testamento olografo, art. 602 c.c.). Drawback: risk of loss or contestation, especially if drafting is ambiguous.
• Notarial testament. Drafted by a notary in the presence of two witnesses (FR) or recorded in the notarial protocol (CH/DE/IT). Maximum evidentiary force, secure deposit, archival at the central testament registry (RNT in France, ZTR in Germany, RGT in Italy, cantonal registry in Switzerland). Cost 300 to 1,500 EUR depending on complexity. Recommended if the Bitcoin holdings exceed 50,000 EUR, or if the family situation is complex (blended, expatriated, undivided estate).

Four Bitcoin-specific points to integrate into the testament, whatever the form.

• Explicit designation of bitcoins as a succession asset. Do not stop at "all my belongings to my spouse"; explicitly mention "the bitcoins held in self-custody×Self-custodyModel in which you hold your own private keys. Your bitcoins depend on no third party. This is Bitcoin's founding promise.See in the lexicon →, identified by the public addresses listed in the sealed annex". This annex never contains private keys, only public addresses as proof of ownership.
• Appointment of a crypto-competent executor. Trusted person familiar with Bitcoin (friend, brother, advisor), distinct from the main legatee. Mission: assist the notary with the tax return, accompany the successor in the technical recovery, verify×Don't trust, verifyBitcoiner mantra. Trust no one (bank, government, exchange, influencer), verify on your own through your own node.See in the lexicon → the multisig×Multisig (multi-signature)Configuration where a transaction must be signed by several independent keys to be valid (for example 2 of 3). Reduces the risk that a single key theft causes loss of funds.See in the lexicon → works. Compensation can be provided (lump sum or percentage), conventionally 1 to 3 %.
• Reference to an instruction kit. The testament indicates the existence of a separate document, titled for example "Bitcoin succession kit", specifying its physical location (bank safe, home safe, notarial office) and the access procedure. This kit describes the technical topology without revealing keys (cf. section 6).
• Annual update clause. Mention that technical elements (addresses, multisig, custodians) will be updated yearly and that the latest available version prevails. Prevents the testament from going obsolete as your setup evolves.

A testament can be modified at any time, without formalism if holographic. Basic rule: reread and sign a new version every year, ideally on the same day as your annual Bitcoin security audit (cf. the security article). Twenty minutes a year to avoid a succession blocked for months.

Heir multisig: the reference technical solution

The best technical approach to transmit bitcoins without revealing the key during your lifetime is heir multisig×Multisig (multi-signature)Configuration where a transaction must be signed by several independent keys to be valid (for example 2 of 3). Reduces the risk that a single key theft causes loss of funds.See in the lexicon →. The principle is simple. A 2-of-3 multisig wallet×WalletSoftware or device that manages your Bitcoin keys and lets you sign transactions. A wallet does not really « hold » your bitcoins, it holds the keys that prove you own them.See in the lexicon → is created with three signers: you, your spouse, and a trusted third party (lawyer, notary, brother). Any transfer requires two signatures out of three. While you are alive, you and your spouse sign together, the third party does nothing. On your death, your spouse and the third party sign together to take back control. The same logic works if you are a sole holder: replace the spouse with a second third party (second brother, friend, notary).

Why 2-of-3 rather than something else? Single-failure tolerance: losing one of three keys does not block anything. Single-betrayal tolerance: a single compromised or malicious signer cannot sign alone. Simple geographic distribution: three distinct physical sites are enough (your home, your spouse's safe in another city, the notary's office). It is the right balance between redundancy and operational simplicity.

Three services and one DIY tool share this market in 2026.

Three architectures work in practice depending on your situation.

• Couple without adult children, medium holdings. 2-of-3 between you, your spouse and a notary. The notary receives one key sealed in an envelope with instruction "open on proof of death or joint request of both spouses". Annual notary fees 100-300 EUR. Simple, robust, legally framed.
• Couple with adult children. 2-of-3 between you, your spouse and a trusted adult child. Variant 3-of-5 between you, your spouse and three children. Geographic distribution is essential: if the three children live in the same city and use the same cloud, decentralisation is illusory.
• Significant holdings and blended family. 3-of-5 with services like Casa (you + spouse + 2 geographically separated hardwares + 1 key with Casa used only on proven incapacity). Casa offers an inheritance protocol with identity verification and configurable waiting period.

The most frequent mistake with heir multisig: not documenting the BIP380 descriptor. The descriptor is the technical string that describes the combination of public keys, derivation paths and address types. Without that descriptor, even with the 3 keys, you cannot rebuild the wallet. The descriptor must appear in the successor instruction kit, in plain text, on paper, in several physical locations. It is public, hence safe, unlike the private keys.

Time-lock, dead man's switch and Shamir SSS

Beyond heir multisig×Multisig (multi-signature)Configuration where a transaction must be signed by several independent keys to be valid (for example 2 of 3). Reduces the risk that a single key theft causes loss of funds.See in the lexicon →, three complementary mechanisms cover edge cases. None replaces multisig, but each adds an extra layer.

Time-lock×Time-lockTime lock that prevents a transaction from being spent before a given date or block. Used for inheritance or assisted recovery.See in the lexicon → by script. Bitcoin natively supports two time-lock opcodes: CHECKLOCKTIMEVERIFY (CLTV, absolute block height) and CHECKSEQUENCEVERIFY (CSV, relative delay since last move). A script can be designed so that funds become spendable by your heir only after an inactivity period (for example 6 months without a transaction signed by you). Advantages: trustless, automatic, no intermediary. Drawbacks: technical complexity (Miniscript and Liana are the practical front-ends in 2026), risk of forgetting if you cross the time-lock boundary before signing a refresh transaction. Relevant for significant holdings and genuinely advanced users.

Digital dead man's switch. The principle: a service periodically asks you to confirm (monthly, quarterly) that you are alive. If you do not confirm, the service automatically sends pre-recorded instructions to your heirs. The Sarcophagus protocol offers an on-chain version (on Arbitrum, with archeologists holding a fragment of the decryption key). Casa Recovery offers a simpler centralised version. Strong limit: you entrust to a third party (centralised or decentralised) the trigger of the transmission. To be combined with multisig, never used alone as a sole device.

Shamir Secret Sharing (SSS). A single seed can be split into N shares of which K are needed to rebuild it. Example: seed split into 5 shares, 3 required to reconstitute. Trezor×Ledger, Trezor, Coldcard, BitBoxMain hardware wallet brands. Ledger Nano S Plus / X (French, the best-seller), Trezor Model T (Czech, open source), Coldcard Mk4 (Canadian, ultra-secure, Bitcoin-only), BitBox02 (Swiss, open source).See in the lexicon → implements SLIP-39 (standardised SSS variant for Bitcoin). Not to be confused with multisig: with SSS, reconstitution exposes the key in cleartext on the assembling device. Multisig, on the contrary, signs without ever reconstituting the key. SSS remains useful for sharing the seed itself between custodians without risk that a single custodian can access alone.

Three recommendations to combine these tools.

• 2-of-3 multisig as foundation. Always. It is the first-line defence, robust, legally understandable.
• Time-lock as a safety net. In complement, for the case where all three multisig signers disappear simultaneously (rare family catastrophe but theoretically possible). A time-locked key that becomes usable after 2 years of inactivity, deposited with a notary with instructions to a distant cousin.
• SSS to split and share an old historical seed. If you have an isolated 2013 Bitcoin seed on paper, SSS lets you fragment it into 5 shares and distribute them to 5 custodians, without revealing the totality to any one. To be reconstituted on D-day by the heir who gathers the 3 shares.

The successor instruction kit

The multisig×Multisig (multi-signature)Configuration where a transaction must be signed by several independent keys to be valid (for example 2 of 3). Reduces the risk that a single key theft causes loss of funds.See in the lexicon → works, the testament is signed, the executor is appointed. The keystone remains: the instruction kit your successor will discover after your death. A well-made kit lets someone who has never used Bitcoin recover the funds within a few weeks by following a manual. An absent or sloppy kit leaves the bitcoins inaccessible, despite all the keys being assembled.

Seven sections to integrate into the kit, in this order.

1. Introductory letter in plain language. First page, written for someone who does not know what a seed is. Explain in 10 lines: what bitcoins are, that they exist in self-custody×Self-custodyModel in which you hold your own private keys. Your bitcoins depend on no third party. This is Bitcoin's founding promise.See in the lexicon →, that they have a market value to verify×Don't trust, verifyBitcoiner mantra. Trust no one (bank, government, exchange, influencer), verify on your own through your own node.See in the lexicon → on D-day, and that they are recoverable by following the steps below. Mandatory mention: "Do not hastily type the elements below into an unverified device. First contact [name of executor] who will guide you."
2. Device topology. Simple hand-drawn diagram explaining that the bitcoins live in a 2-of-3 multisig wallet×WalletSoftware or device that manages your Bitcoin keys and lets you sign transactions. A wallet does not really « hold » your bitcoins, it holds the keys that prove you own them.See in the lexicon →, that the three keys are at locations A, B, C, and that two keys out of three are enough to sign. Essential for the successor to understand where to look and how many they need.
3. Physical locations of keys and backups. Home safe (combination or physical key with X), bank safe (number, authorised mandataries), notary's office (Me Y, city Z, contact). For each location, what is found there (key 1, paper backup of seed 1, printed BIP380 descriptor, etc.). Never the seeds or keys themselves in this document: locations only, not secrets.
4. BIP380 descriptor of the multisig wallet. Full text of the descriptor, hand-copied legibly and printed. It is public, so risk-free. Without this descriptor, even with the 3 keys, the wallet is unrecoverable.
5. Technical step-by-step instructions. Install Sparrow Wallet or Specter Desktop on a clean computer. Import the descriptor. Recover the hardware wallets. Sign with two of the three keys. Build the sweep transaction to an address controlled by the heir. Broadcast. Strongly recommend doing these steps with the crypto-competent executor.
6. Useful contacts. Notary (with direct phone if possible), crypto-competent executor, tax advisor familiar with crypto taxation, possibly a lawyer. Mention who to contact first and for what.
7. Tax and reporting instructions. Briefly: bitcoin value is to be included in the succession asset at the day-of-death value. Reference to the relevant tax-code articles of the country. Indicate whether an RW (Italy) or 3916-bis×3916-bisFrench tax form used to declare crypto accounts held abroad. Omitting it is fined at 750 EUR per undeclared account.See in the lexicon → (France) declaration is due by the heir after transmission.

Practical format. Paper, printed and signed, in 3 copies: 1 to the notary, 1 in the home safe, 1 with the executor. No cloud PDF, no Google Drive: a shared digital kit can be read by an attacker and used to target the future successor, or render the succession blocked if the cloud account is inaccessible. On paper, signed, dated, updated annually.

Edge cases and pitfalls to avoid

Six specific situations deserve standalone thinking, because they break the assumptions of standard heir multisig×Multisig (multi-signature)Configuration where a transaction must be signed by several independent keys to be valid (for example 2 of 3). Reduces the risk that a single key theft causes loss of funds.See in the lexicon →.

• Non-bitcoiner×BitcoinerPerson interested in Bitcoin, who holds some and adheres more or less to its values (individual sovereignty, sound money, decentralisation).See in the lexicon → spouse. The risk is to set up a 2-of-3 multisig where the spouse is a signer but does not know how to use it. Solution: double up with practical training. Organise an annual session where the spouse signs a real test transaction (send 50 EUR round trip), so they know the mechanics before it becomes critical. Keep a step-by-step sheet in the instruction kit.
• Minor heir. If your children are minors, they cannot directly inherit the responsibility of a key. Solution: the key is entrusted to a testamentary guardian (named in the testament), who holds the key in trust until the child's majority. Combining with a time-lock×Time-lockTime lock that prevents a transaction from being spent before a given date or block. Used for inheritance or assisted recovery.See in the lexicon → to forbid withdrawals before 18 or 21 can be relevant.
• Foreseeable family conflict. Feuding siblings, litigious ex-spouse, contentious undivided estate. Multisig with a neutral notary as third key becomes critical. The notary signs only on legal proof (death, judgment) and arbitrates between heirs in case of disagreement. Extra cost but strong protection.
• Non-crypto executor. If you name your family notary or usual lawyer as executor without them knowing Bitcoin, they will be overwhelmed. Solution: co-execution. The legal executor handles the testament, and a crypto-competent co-executor handles the technical part. The two work together. Provide for it explicitly in the testament.
• Loss of capacity (Alzheimer, stroke, coma). You are alive but unable to sign. Standard multisig does not trigger transmission in this case, because everyone awaits your death. Solution: a future-protection mandate (CH/FR), Vorsorgevollmacht (DE), amministrazione di sostegno (IT). Legal document that names, on proven incapacity by medical certificate, a representative who can sign on your behalf, including on Bitcoin assets. To combine with a specific multisig clause in the mandate.
• Divorce before testament update. The testament remains valid after divorce but may name an ex-spouse who is no longer a legal heir. Worse, in some countries (Switzerland), divorce automatically cancels dispositions in favour of the ex-spouse but not the others. On every family-situation change, review testament and multisig. The annual audit rule helps not to forget it.

Five classic pitfalls to know to avoid them.

• Memorised passphrase×PassphraseExtra word or phrase you add to your seed phrase to create a hidden wallet. Optional security layer, independent of the seed.See in the lexicon → not transmitted. If you use a BIP39×BIP39Standard defining the list of 2,048 words used for seed phrases. Lets every wallet brand generate seeds that are compatible with each other.See in the lexicon → passphrase, it must be somewhere. The rule "the passphrase stays in my head" is compatible with your lifetime security but destroys transmission. Solution: back up the passphrase in parallel, on paper, separate from the seed, in a location different from the multisig. Ideally with the notary in a sealed envelope.
• Multisig created but undocumented. Frequently seen case: a user builds a technical multisig without writing the instruction kit. On death, heirs have the 3 hardwares but without the BIP380 descriptor or the procedure, they can do nothing. Technique without documentation = guaranteed loss.
• Succession blocked by lack of liquidity. Inheritance taxes are paid in EUR/CHF, not BTC, and the administration wants its payment before unlocking the asset. If the entire wealth is in illiquid bitcoins at a downturn moment, heirs may have to sell at bad timing to pay duties. Provide a cash or life-insurance reserve to cover estimated duties.
• Jurisdiction mistake. Applicable tax is that of the deceased's country of residence, not the country where the bitcoins are "located" (a notion that makes no sense in cryptography). A French person residing in Geneva is subject to Geneva taxation, not French. A German residing in Lisbon is subject to Portuguese taxation. Anticipate consequences before expatriation.
• Succession freezing period. Average 6 to 12 months between death and effective liquidation in the euro zone. During this period, heirs cannot touch the multisig without notarial authorisation. Consistent with procedure, but to anticipate if heirs count on the funds to live.