What is multisig?

A wallet setup that requires more than one private key to authorize a transaction, such as two signatures out of three keys.

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A wallet setup that requires more than one private key to authorize a transaction, such as two signatures out of three keys.

Multisig removes the single point of failure of one key and is standard for organizations, treasuries, and custodians. It also appears in personal setups where someone wants a backup key held in a different place, and in escrow arrangements where a third party can break a tie.

The setup is described by two numbers, written as m-of-n: how many signatures are required, out of how many keys exist. Two-of-three is the common choice because it survives losing one key and still requires two to steal. Losing too many of the keys makes the funds unrecoverable, and that is the failure mode that actually happens.

How it works

The arrangement is enforced by the blockchain rather than by an application. On Bitcoin it is expressed in the output script, so the network itself refuses to accept a spend without the required signatures. On Ethereum it is a smart contract that holds the funds and counts approvals before executing.

Signing is a sequence rather than a moment. One holder constructs the transaction, signs, and passes the partially signed transaction to the next. On Bitcoin the standard container for that hand-off is a partially signed Bitcoin transaction, specified in Bitcoin Improvement Proposal 174. Once the threshold is met, anyone can broadcast it.

The keys should be independent in every sense that matters: different devices, different locations, and ideally different manufacturers, since a shared vulnerability across identical hardware defeats the purpose. Keys held on three phones in one bag is a one-of-one wallet with extra steps.

Recovery needs planning up front. For Bitcoin you generally need the wallet descriptor or the extended public keys as well as the seeds, because the software must reconstruct the exact script to find the funds. Storing that descriptor alongside the backups is part of the setup, not an optional extra.

Example

Illustrative two-of-three arrangement for a personal holding. Key one is a hardware wallet at home. Key two is a second hardware wallet in a bank deposit box. Key three is held by a trusted family member or a recovery service.

Day to day, keys one and two sign. If the house is burgled and key one is taken, the thief has one signature and cannot spend, while you still have keys two and three to move the funds to a new wallet. If you die, the family member and the deposit box together reach the funds without you. The cost of this is real: three backups to maintain, a descriptor to store, and a signing process that takes minutes rather than seconds.

Why it matters when you buy

Multisig matters after you buy, not during. It is the standard answer to holding a meaningful amount in self-custody without a single seed phrase being fatal to lose or catastrophic to have found. It is also worth knowing which exchanges publish their own custody arrangements, since multisig or its cryptographic cousin is what sits behind a venue's cold storage. Those disclosures are recorded at the exchange directory, and our walkthrough is at Multisig basics.

Questions

Is multisig worth it for a small amount?

Usually not. The added backup complexity introduces its own failure modes, and for smaller holdings a single well-backed hardware wallet is simpler and safer in practice.

Does multisig cost more in fees?

On Bitcoin, yes, because the transaction carries more signature data and fees are charged by size. On Ethereum the contract execution also costs more than a simple transfer.

What is the difference between multisig and a shared account?

Multisig is enforced by the blockchain: no threshold, no spend. A shared exchange account is enforced by the exchange's software and permissions, and the exchange can override it.

Guides that use this term

  • How to Set Up a Hardware Wallet

    Setting up a hardware wallet takes five steps: buy the device new from the manufacturer, initialize it yourself so it generates its own keys, write the recovery phrase on paper offline, set a PIN, and restore the wallet from that written phrase before you move any real money onto it.

  • What Happens If You Lose Your Seed Phrase

    If you lose the seed phrase for a self-custody wallet and no other copy exists, the funds stay visible on the blockchain and become permanently unspendable, because nobody, including the wallet maker, holds a second copy of the key or any authority to reset it.

  • Multisig Wallets for Families and Small Businesses

    A multisig wallet requires several separate keys to approve a transaction, usually two of three, which means one lost or stolen key does not lose or expose the funds, and that property is what makes it worth the extra setup for family savings and small business treasuries.

  • How to Back Up a Seed Phrase: Paper, Metal, and Split Backups

    A seed phrase backup has to survive fire, water, theft, and your own filing habits, which is why the three practical options are paper stored in more than one place, a stamped or engraved metal plate, and a split backup that requires several shares to reconstruct the secret.

  • Self-Custody vs Exchange Custody: How to Decide

    Deciding between self-custody and exchange custody means choosing which failure you would rather be exposed to, a company that loses or freezes your assets or a mistake of your own that nobody can undo, and most people resolve it by splitting holdings rather than picking one for everything.