Collaborative custody is a Bitcoin custody architecture in which the holder controls the majority of the keys in a multi-signature arrangement and a service provider holds one key as a co-signer. The defining property is that the holder retains direct cryptographic control of the Bitcoin: any transaction requires at least one of the holder's keys, and the provider cannot move funds unilaterally. The provider's role is to coordinate the multisig, hold a backup key for recovery, support signing operations, and provide a service layer around the arrangement. Collaborative custody sits between self-custody, where the holder controls every key alone, and institutional models, where the holder controls none.
The standard implementation is a 2-of-3 multisig. The holder holds two of the three keys; the provider holds the third. Spending requires any two keys, so the holder can transact using their two keys alone, the provider can never spend without the holder, and if the holder loses one key, the provider's key plus the holder's remaining key can still recover the funds. Higher-quorum variants (3-of-5) exist for larger holdings or more complex recovery and inheritance arrangements.
The two best-known collaborative custody providers implement the model differently in their details.
Unchained uses a 2-of-3 multisig in which the client holds two hardware-wallet keys and Unchained holds one as a backup co-signer. The client retains direct control; Unchained cannot move funds without the client. Unchained layers Bitcoin-native services on top of the arrangement, including IRAs, Bitcoin-backed lending, trust integration, and, more recently, transfer-on-death beneficiary designation for vaults.
Casa offers a 2-of-3 vault on its Standard tier and a 3-of-5 vault on its higher tier. In the 3-key configuration, one key lives on the holder's phone in the Casa app, one on a hardware wallet, and one is held by Casa as a recovery key. Casa emphasizes user experience, key recovery, and an inheritance product built around a deadman-switch model rather than a probate-document process.
In both cases, the architecture preserves the holder's direct cryptographic control while adding a professional partner for recovery and coordination. The holder is one of the signers, which is the property that distinguishes collaborative custody from every institutional model.
Collaborative custody is best understood by what it provides and what it requires in return.
What it provides:
What it asks of the holder:
Inheritance is where the collaborative model's details matter most, and where the two leading providers have taken different approaches worth understanding.
Casa's Standard three-key inheritance is designed so that heirs do not need to operate a hardware wallet. The heir uses a mobile key plus the Casa Recovery Key to access the vault, and the transfer runs on a deadman-switch model: after a defined inactivity period (six months), with no response from the original holder, vault access passes to the recipient, without requiring probate documents or a death certificate. This is a meaningful design choice, because the most common criticism of collaborative custody for inheritance, that it assumes heir technical competence, does not apply to this configuration.
Unchained offers transfer-on-death beneficiary designation for vaults, which passes the Bitcoin outside probate. The heir needs to locate at least one seed-phrase backup, and Unchained guides the claim process. This requires somewhat more heir involvement than Casa's mobile-key model but remains far short of expecting an heir to independently operate a multisig.
Both approaches address the legal-title and continuity problems that a generic "leave your heir the seed phrase" plan does not. Proof of Custody's full evaluation of inheritance across providers is in the Bitcoin Inheritance Scoring Methodology.
Collaborative custody is the strongest fit for:
It is a weaker fit for holders who want zero operational responsibility (qualified custody or MIC fit better), for holders with heirs who could not operate any part of the arrangement (though Casa's Standard inheritance mitigates this), and for the smallest positions where the service cost outweighs the benefit.
Is collaborative custody the same as multisig?
Collaborative custody is built on multisig, but multisig is the broader cryptographic primitive. Multisig simply means more than one key is required to spend. Collaborative custody is a specific application in which the holder controls most of the keys and a provider holds one as a co-signer. Multi-institution custody is a different application of multisig in which all the keyholders are independent institutions and the holder holds none.
Can the provider take my Bitcoin in collaborative custody?
No. In a 2-of-3 arrangement where the holder holds two keys, the provider holds only one and cannot meet the two-key spending threshold alone. The provider cannot move funds without the holder's participation.
What happens if the collaborative custody provider goes out of business?
Because the holder controls the majority of keys, the holder can recover the Bitcoin even if the provider disappears, using the holder's own keys and, where needed, the provider's published recovery procedures. This is a core advantage of the holder holding most of the keys.
Is collaborative custody good for inheritance?
It can be, depending on the provider's implementation. Casa's Standard inheritance does not require heirs to operate a hardware wallet, and Unchained offers transfer-on-death beneficiary designation. Both address the legal-title and continuity problems better than an unstructured self-custody plan. The key question is what the specific heir would have to do operationally, which is evaluated in the Bitcoin Inheritance Scoring Methodology.
Collaborative custody is the model for holders who want to keep direct control of their Bitcoin while gaining a professional partner for recovery and continuity. It preserves the holder's key participation, which is its defining strength and, for some holders and some inheritance situations, its defining limitation. It is distinct from multi-institution custody, where the holder holds no keys, and from qualified custody, where one institution holds all of them. Holders choosing among custody models should decide first whether direct key participation is something they want to retain; that single question separates collaborative custody from the institutional alternatives.
Related reading:
Editorial note: This explainer is editorially independent. Provider implementation details (Casa, Unchained) were verified against current provider documentation in June 2026. See Editorial Independence.
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