# Multisig

Multisig requires several keys to sign, such as 2 of 3, removing single points of failure for theft and loss. Learn how to set it up safely.

Canonical page: https://mybitcoinexplorer.com/learn/multisig
Topic: Bitcoin Script
Published: 2026-10-29
Updated: 2026-10-30


## Several keys, one lock
A multisig output requires **m** signatures from a set of **n** keys: for example 2-of-3.

> Diagram: A 2-of-3 output: any two of the three keys can spend — 2of3

## Why use it?
- **No single point of theft:** one stolen key isn't enough.
- **No single point of loss:** lose one key and the other two still work.
- **Shared control:** a business can require two directors, or an inheritance plan can include a lawyer as the third key.

## How it's built
Classic multisig uses `OP_CHECKMULTISIG`:

~~~
2 <pubkey A> <pubkey B> <pubkey C> 3 OP_CHECKMULTISIG
~~~

It's normally wrapped in [Pay to script hash (P2SH)](https://mybitcoinexplorer.com/learn/p2sh) or P2WSH so the long script is hidden behind a hash until spending.

With [Taproot](https://mybitcoinexplorer.com/learn/taproot), multisig can use `OP_CHECKSIGADD` in a script path, or [MuSig2](https://mybitcoinexplorer.com/learn/schnorr-signatures) key aggregation, so an n-of-n spend looks like a single signature.

## The backup catch
To restore a multisig wallet you need enough seeds **and** every co-signer's public key (or the wallet's descriptor). Back that information up too. See [How to back up a Bitcoin wallet](https://mybitcoinexplorer.com/learn/backing-up-a-wallet).


## Example setups
| Setup | Who holds keys | Protects against |
|---|---|---|
| 2-of-3 personal | You: two devices plus one backup elsewhere | One lost or stolen device |
| 2-of-3 shared | You, your partner, a trusted third party | One person losing access |
| 3-of-5 company | Five directors | Fraud by up to two people |

## Common mistakes
- Keeping all keys in the same house.
- Backing up seeds but not the wallet descriptor or the other xpubs.
- Never testing a recovery.


## Key takeaways

- Multisig needs m of n keys to spend.
- It protects against both theft and loss of a single key.
- Back up the descriptor or all xpubs, not only the seeds.

## Common questions

### Is multisig more expensive?

Yes, spending carries several signatures and keys. Taproot key aggregation can reduce this a lot.

### What's the most popular setup?

2-of-3 is common: it tolerates one lost key and one stolen key.

### Is multisig only for businesses?

No. Many individuals use 2-of-3 for savings.

### Does multisig cost more in fees?

Classic multisig does. Taproot-based setups can make it as cheap as a single-signature spend.

## Related lessons

- [Pay to script hash (P2SH)](https://mybitcoinexplorer.com/learn/p2sh)
- [Taproot](https://mybitcoinexplorer.com/learn/taproot)
- [Schnorr signatures](https://mybitcoinexplorer.com/learn/schnorr-signatures)
- [Hardware wallets](https://mybitcoinexplorer.com/learn/hardware-wallets)