A 2 of 3 multisig: what happens when a key is lost or stolen

A 2 of 3 multisig wallet needs any two of three keys to approve a payment. That one rule gives a company two protections at once: no single person can move funds alone, and losing one key does not lose access. Pick a set-up and an event below to see what still works and what recovery needs.

Source: Bitcoin BIPs: BIP 11: M of N standard transactions (multisig).

The two set-ups

Self-managed. Two directors each hold one key on their own signing device. A third, backup key is kept in a separate location under the company's control. Any two keys can sign. See self-managed multisig in the custody guide.

Collaborative. The company holds two keys and a specialist provider holds the third. The provider can help with recovery or co-sign under agreed conditions, but cannot move funds alone. See collaborative multisig.

The scenarios in words

• Lose a key (its device and its written backup are both gone): the other two keys can still sign. Move the funds to a new 2 of 3 wallet with a fresh third key, then update the key register.
• A key is stolen (someone else has a signing device or its written backup): one key on its own cannot move funds in a 2 of 3, so the thief cannot spend alone. Treat that key as exposed. Use the two keys the company still controls to move the funds to a new 2 of 3 wallet that does not include the exposed key, then update the key register.
• A director leaves: the key they held should no longer be relied on. The remaining two keys sign a move to a new wallet that does not include the old key, and a replacement keyholder gets a new key.
• A device fails: the key is not lost if its recovery words were backed up. Restore the key onto a new device from its backup, and test it with a small amount. Meanwhile the other two keys can still sign.
• The provider disappears (collaborative only): the company still holds two keys, which is enough to sign. To rebuild the wallet in other software, the company needs its wallet descriptor backup, which records all three public keys and the script.
• Two keys lost at once: funds cannot move until at least one of the lost keys is restored from its backup. One key alone can never move funds in a 2 of 3. That is the design working as intended, and it is why each key needs its own backup in a separate place and why recovery is tested.

Source: Bitcoin BIPs: BIP 11: M of N standard transactions (multisig), Bitcoin BIPs: BIP 39: Mnemonic code for generating deterministic keys, Bitcoin BIPs: BIP 380: Output script descriptors, general operation (wallet backups and exports), Bitcoin BIPs: BIP 174: Partially Signed Bitcoin Transaction format (PSBT).

Why there is no single-key option here

We do not recommend a single-signature wallet for a company treasury: one device, one backup and usually one person control everything, with no second check before funds move. The custody guide explains why.

Because no single keyholder can move funds alone, a 2 of 3 also protects the people who hold the keys. See keyholder safety and privacy.

Where to go next

• Key ceremony walkthrough: setting up a company 2 of 3 step by step.
• Keyholder continuity: when a keyholder leaves, is ill or dies.
• Glossary: multisig, descriptor and recovery phrase.

Sources

Primary sources only. Each link was checked on 29 October 2026. Rules change, so confirm the current version with your adviser.

1. Bitcoin BIPsBIP 11: M of N standard transactions (multisig)
2. Bitcoin BIPsBIP 39: Mnemonic code for generating deterministic keys
3. Bitcoin BIPsBIP 174: Partially Signed Bitcoin Transaction format (PSBT)
4. Bitcoin BIPsBIP 380: Output script descriptors, general operation (wallet backups and exports)
5. Bitcoin BIPsBIP 32: Hierarchical deterministic wallets (extended keys)

Next step: your own node. Once the keys, backups and drill are in place, a company can check the chain itself. Running your own bitcoin node.

Timelocked recovery for company bitcoin: delayed threshold paths, per-output clocks and the maintenance they require.