Multisig Inheritance Planning Guide

The Problem Multisig Solves for Inheritance

Bitcoin’s greatest strength — no intermediary can seize or freeze your funds — becomes its greatest weakness when you die. A bank can release funds to heirs with a death certificate. Bitcoin does not care about death certificates. If your heirs do not have the private keys and the knowledge to use them, your bitcoin is lost permanently.

Multisig addresses this by distributing keys across people and locations. A well-designed 2-of-3 or 3-of-5 setup ensures that your heirs can access funds even if you are unable to hand over keys personally, while preventing any single person from accessing the bitcoin prematurely. This guide covers the strategies, tools, and practical steps for making your bitcoin inheritable.

Why Standard Single-Sig Fails for Inheritance

With a standard single-signature wallet, you face an impossible dilemma:

• Share your seed phrase with an heir — They can access your bitcoin at any time, including while you are alive. You are trusting them completely.
• Lock your seed phrase in a safe with a letter — Your heirs must find it, understand what it is, and know how to use it. Non-technical heirs may fail at multiple points.
• Tell no one — Your bitcoin dies with you.

A multisig configuration breaks this deadlock. You can distribute keys so that your heirs need cooperation from a trusted party — an attorney, a custody service, or another family member — preventing unilateral access while ensuring recovery is possible.

Inheritance-Optimized Key Distribution

The 2-of-3 Inheritance Model

Under normal conditions, you spend using Key 1 plus Key 3 (or Key 1 plus Key 2 if Key 3 is unavailable). After your death, your heir uses Key 2 plus Key 3 to access the funds. The attorney or custody service verifies the death before co-signing.

The 3-of-5 Model for Larger Estates

A 3-of-5 setup provides greater flexibility for complex family situations or larger holdings. Multiple combinations of signers can authorize transactions, reducing the chance of permanent loss from any two keys being unavailable.

Dead Man’s Switch Options

A dead man’s switch is a mechanism that triggers action if you stop responding. For bitcoin inheritance, this means initiating the key transfer process automatically when you can no longer do it yourself.

Email-Based Dead Man’s Switch

Services like Google’s Inactive Account Manager or dedicated dead man’s switch services (such as Dead Man’s Button or IfIDie) send pre-written emails to your heirs after a period of inactivity. You configure:

1. An inactivity period (e.g., 90 days without a check-in).
2. The recipient (your heir).
3. The message content (instructions for accessing bitcoin, location of keys, wallet configuration file).

The email does not contain the seed phrases themselves — it points to their physical locations and provides step-by-step instructions. This separates the “how” from the “where,” reducing the risk of a compromised email account leading to theft.

Collaborative Custody Dead Man’s Switch

Services like Casa include a built-in inheritance protocol. If you stop responding to periodic health checks, Casa initiates a waiting period and then transfers co-signing authority to your designated heir. Because Casa holds only one key in a 2-of-3 or 3-of-5 setup, this process requires the heir to also provide their key — no single party gains unilateral control.

Manual Dead Man’s Switch (Low-Tech)

For those who prefer no third-party services:

1. Prepare sealed envelopes containing instructions (not seed phrases).
2. Give them to your heir and attorney with instructions to open only upon death.
3. Each year, check in with your heir and attorney to confirm you are alive and the plan is current.
4. If they do not hear from you for a set period, they open the envelopes and follow the instructions.

Writing a Letter to Your Heirs

The letter is the most important part of your inheritance plan. A technically perfect multisig setup is worthless if your heirs cannot understand or execute the recovery steps. Write the letter assuming your heir has zero bitcoin knowledge.

What the Letter Should Include

1. An explanation of what bitcoin is — One paragraph. They do not need a deep understanding, just enough to know this is real money and worth recovering.
2. The approximate value — Give them motivation to follow through. “As of [date], this wallet holds approximately $X worth of bitcoin.” Update this annually.
3. The location of each key — Specific physical locations: “Key 1 is in the fireproof safe in the basement, inside the silver Cryptosteel capsule.” Include photos if helpful.
4. The wallet configuration file — Attach a copy or specify where one is stored. Explain that this file, combined with any two of the three keys, is needed to access the funds.
5. Step-by-step recovery instructions — Written for a non-technical person:
   • Download Sparrow Wallet from sparrowwallet.com (include how to verify the download).
   • Import the wallet configuration file.
   • Connect two of the three hardware wallets or enter two seed phrases.
   • Send the bitcoin to [exchange account / new wallet / desired destination].
6. Contact information for your custody service — If using Casa, Unchained, or an attorney, provide their contact details and account information.
7. A trusted technical contact — Name a bitcoin-savvy friend or advisor your heirs can call for help. Pay this person a retainer or include them in the inheritance plan.

Store copies of this letter alongside at least two of the three keys (but never in the same location as the seed phrases themselves). The seed phrase security guide covers physical storage best practices.

Time-Locked Transactions

Bitcoin supports time-locked transactions at the protocol level. These transactions are valid but cannot be included in a block until a specified time or block height. For inheritance, time-locked transactions offer a programmatic dead man’s switch.

How Time-Locked Inheritance Works

1. Create a transaction that sends your bitcoin from your current wallet to your heir’s address.
2. Set the nLockTime to a date 6–12 months in the future.
3. Sign the transaction and give the signed (but unbroadcast) transaction to your heir.
4. Every 6 months, move your bitcoin to a new address, which invalidates the old time-locked transaction.
5. Create a new time-locked transaction pointing to the new address and give it to your heir.

If you stop refreshing the time-locked transaction (because you are incapacitated or dead), your heir can broadcast the last valid transaction after the lock time passes. If you are alive and active, the transaction is always invalid because the UTXO it references has already been spent.

Limitations of Time-Locked Transactions

• Maintenance burden — You must refresh the transaction every cycle. Missing a refresh means your heir could access funds early.
• Single-sig dependency — The time-locked transaction is signed with your key. If combined with multisig, the heir still needs the required number of signatures.
• Fee uncertainty — The fee rate is fixed when you sign the transaction. If fees increase dramatically by the time the heir broadcasts, the transaction may take a long time to confirm or fail to propagate.

Time-locked transactions work best as a complementary mechanism alongside a multisig inheritance plan, not as the sole strategy.

Inheritance Services

Casa

Casa’s inheritance protocol integrates with their collaborative custody model. In a 2-of-3 or 3-of-5 setup, Casa holds one key. Their inheritance plan designates a beneficiary who goes through a verification process (identity verification, waiting period) before Casa co-signs the beneficiary’s transaction. The entire process is designed so that Casa alone never controls the funds.

Cost: Monthly subscription ($250+/year for inheritance-tier plans). The self-custody security analysis evaluates Casa’s model in depth.

Unchained Capital

Unchained offers a similar collaborative custody model with formal inheritance documentation. Their service includes legal templates, a designated beneficiary process, and key holder verification. Unchained holds one key in a 2-of-3 setup and assists with co-signing during inheritance events.

Attorney-Based Approach

An estate attorney can hold a sealed copy of one key as part of your will or trust documents. Benefits include legal privilege and established fiduciary obligations. Risks include the attorney not understanding bitcoin technology, losing the key, or mishandling it during probate.

If using an attorney, consider a sealed tamper-evident bag containing the seed phrase backup, labeled with instructions and the attorney’s role in the multisig setup. Include a copy of the wallet configuration file with the attorney’s materials.

Testing Your Inheritance Plan

An untested inheritance plan is not a plan — it is a hope. Test it while you are alive.

1. Create a test multisig wallet with a small amount of bitcoin (50,000–100,000 sats).
2. Give your heir the recovery instructions without any additional guidance.
3. Ask them to recover the funds using only the written instructions and the designated keys.
4. Observe where they struggle and rewrite those sections of the letter.
5. Repeat until they can do it independently.

This rehearsal reveals gaps that are invisible on paper: software installation issues, firmware update prompts on hardware wallets, seed phrase entry confusion, and address verification hesitation. Fix these gaps before they matter.

Ongoing Maintenance

Your inheritance plan requires periodic maintenance:

• Annual review — Verify that keys are still in their designated locations, hardware wallets still function, and backup materials are intact.
• Software updates — Ensure the coordinator software (Sparrow, Nunchuk) is still available and compatible. Consider keeping an offline installer as backup.
• Life changes — Marriage, divorce, birth of children, and death of designated key holders all require updating the plan.
• Update the letter — Approximate portfolio value, wallet software instructions, and contact information for trusted advisors change over time.
• Firmware updates on hardware wallets — Update annually to maintain security. Check firmware update best practices before applying.

Frequently Asked Questions

Can I just include my seed phrase in my will?

Wills become public record during probate in most jurisdictions. Including a seed phrase in a will exposes it to court officials, attorneys, and potentially the public. Use the will to reference the location of sealed materials instead — “I direct my executor to retrieve the sealed envelope from safe deposit box #XYZ at [bank].”

What if my heir loses their key before I die?

In a 2-of-3 setup, you still have two keys and can create a new multisig wallet with a replacement key. Transfer funds from the old wallet to the new one. Give the heir a new key. This is exactly why multisig is better than single-sig for inheritance — you have redundancy.

Should I tell my heirs about the bitcoin while I am alive?

At minimum, one trusted person should know that the bitcoin exists and that an inheritance plan is in place. They do not need to know the exact amount or hold any keys. They just need to know that the sealed instructions exist and where to find them. Discovering bitcoin wealth for the first time during grief makes the recovery process much harder.

How do collaborative custody services handle company failure?

Both Casa and Unchained design their systems so that the client can always recover funds independently. You hold 2 of 3 keys — even if the company shuts down, you can sign with your two keys using any compatible wallet software. The risk is not fund loss but loss of the convenience layer and emergency co-signing service.

Is there a minimum amount of bitcoin where multisig inheritance makes sense?

There is no strict minimum, but the setup cost (hardware wallets, potential custody subscriptions, attorney fees) typically makes sense for holdings above $50,000–$100,000 in bitcoin. Below that, a well-documented single-sig setup with a properly secured seed phrase and a detailed letter may be sufficient.

For a broader perspective, explore our hardware wallet buying guide guide.

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