When Can Co-Trustees Act Independently in California?

In California, a co-trustee generally cannot act independently. Probate Code 15620 requires unanimous agreement among co-trustees for any power they hold jointly, unless the trust document says otherwise.¹ There are two main ways around that default: the trust instrument grants a specific trustee independent authority, or a co-trustee is permanently gone or temporarily unavailable and action is necessary. Outside those paths, one trustee acting alone is acting without authority.

The Default Rule Is Unanimity, Not Majority

Many people assume that with three or more co-trustees, a majority can carry a decision. California law says otherwise. Probate Code 15620 treats any power held by two or more trustees as a joint power exercisable only by unanimous action, regardless of how many trustees are serving.¹

That rule applies to the ordinary business of running a trust: paying bills, moving funds between accounts, making distributions to beneficiaries, selling or buying assets, signing contracts. Every one of those actions, by default, needs every trustee’s agreement. When co-trustees cooperate, that is a formality. When they do not, it is the main reason trusts end up in court.

When the Trust Document Lets One Trustee Act Alone

The trust instrument controls. Because Probate Code 15620 defers expressly to the trust’s terms, a drafter can distribute authority in almost any way the settlor wants.¹

Common arrangements split duties by subject matter, giving one trustee sole authority over investments while another handles distributions. Others let any single trustee handle routine administrative tasks under a dollar threshold, reserving unanimity for larger decisions. A trust with three or more trustees can expressly allow majority rule. A trust can also designate a lead trustee for a given category of transactions, with the others holding veto power only over specified major actions.

California courts generally enforce these arrangements as the trust writes them, so long as nothing in the trust tries to override the mandatory baseline duties under Probate Code 16000 and related sections.² The practical question for any co-trustee asking whether they can act alone is simple: open the trust, find the section on trustee powers and signatures, and read it. If it does not clearly grant you solo authority for the task in front of you, you need the other trustees’ agreement.

Vacancies and Temporary Unavailability

Two statutory exceptions let remaining trustees act without a missing colleague. The first covers permanent vacancies. If a co-trustee leaves office through death, resignation, or removal, the remaining co-trustees can act as if they were the only trustees named, unless the trust says otherwise.³ This keeps the trust running while a successor is identified and appointed.

The second covers temporary unavailability from absence, illness, or other incapacity. The remaining co-trustees can act, but only when action is necessary to carry out the trust’s purposes or to avoid irreparable harm to trust property.⁴ The necessity requirement is a real limit. A co-trustee’s two-week trip abroad does not give the others a window to make discretionary decisions that could reasonably wait for their return.

Real Estate, Banks, and Other Third Parties

Property transactions are the pressure point. The Probate Code grants trustees the power to buy, sell, and exchange trust property under section 16226, and to mortgage or encumber it under section 16228.⁵⁶ Those powers belong to the trustees jointly. Without specific language in the trust giving a co-trustee solo real estate authority, Probate Code 15620 governs, and every named co-trustee has to sign.

Title companies and escrow officers know this and act accordingly. They will typically refuse to close unless every acting trustee signs the deed, or unless a certification of trust clearly establishes that fewer signatures are enough. The certification of trust under Probate Code 18100.5 is the standard way to prove trustee authority to banks, title insurers, and other institutions without handing over the full trust document. One of its required contents is the signature authority of the trustees: whether all must sign, or whether fewer than all can act.⁷

The certification must be signed by all currently acting trustees and executed as an acknowledged declaration. For real property, it can be recorded with the county recorder. A third party who relies on the certification in good faith is protected even if it turns out to be inaccurate, which is why banks and buyers typically accept it instead of demanding the full trust.

What Happens If a Co-Trustee Acts Without Authority

A co-trustee who signs a contract, transfers funds, or sells trust property without the authority to do it alone is exposed on several fronts. The transaction itself can be unwound, especially for real estate, where a title company or a later purchaser can discover the missing signatures through the recorded chain and the certification of trust. Beneficiaries or co-trustees can also petition the probate court under Probate Code 17200 for instructions, to compel accountings, or to challenge the trustee’s conduct.⁸

Acting without authority can also become a ground for removal. Probate Code 15642 allows the court to remove a trustee for breach of trust, for unfitness, and for hostility or lack of cooperation among co-trustees that impairs trust administration. A trustee who repeatedly acts around the other trustees fits that pattern. While a removal petition is pending, the court can suspend the trustee’s powers and order trust property turned over to a co-trustee or temporary trustee.⁹

Financial liability follows if the unauthorized action causes loss. Courts can order the trustee to restore property, return profits, or pay damages, all from personal assets rather than the trust.

The Other Side: You Cannot Just Stay Silent

If you are a co-trustee who assumes the active trustee will handle everything and your signature is a formality, California law disagrees. Probate Code 16013 places two affirmative duties on every co-trustee: participate in administering the trust, and take reasonable steps to prevent a co-trustee from committing a breach or to compel a co-trustee to redress one. Probate Code 16012 adds that a trustee cannot hand off their role; delegation of specific tasks to professionals is allowed with proper supervision, but a wholesale delegation to the other trustee is not.¹⁰

The reason this matters: a passive co-trustee can be held personally liable for the active trustee’s breach. Probate Code 16402 lists the situations, which include participating in the breach, improperly delegating administration, approving or concealing the breach, enabling it through negligence, and knowing or having reason to know about a breach and failing to take reasonable steps to make the other trustee fix it.¹¹ A co-trustee who signs whatever is placed in front of them, or who looks away from warning signs to avoid conflict, falls into the last two categories.

Every co-trustee also carries the standard fiduciary duties individually: loyalty to the beneficiaries and the prohibition on self-dealing under Probate Code 16002 and 16004, prudence in managing assets under Probate Code 16040, and impartiality among beneficiaries under Probate Code 16003.¹²¹³¹⁴¹⁵ A trustee who agrees to a risky investment proposed by their co-trustee without independent diligence can be surcharged for the resulting loss even though the idea was not theirs.

When Co-Trustees Cannot Agree

Deadlock is the predictable result of a unanimity rule, which is why well-drafted trusts include tie-breakers: a mediator or arbitrator, a neutral third party with a deciding vote, or an odd number of trustees with majority rule. If your trust has such a mechanism, use it first.

When the trust is silent and the trustees cannot work it out, any trustee or beneficiary can petition the probate court under Probate Code 17200 to interpret the trust, instruct the trustees, compel a trustee to act, or settle accounts.⁸ Courts can also grant trustees new powers where existing terms have become unworkable, and can remove a trustee under Probate Code 15642 when the hostility between co-trustees is itself the problem.⁹

Litigation is slow and expensive, and the trust pays for it, meaning the beneficiaries do. Mediation first, court second, is almost always the right order even when the trust does not require it.

1
California Legislative Information. California Code Probate 15620 – Cotrustees
2
California Legislative Information. California Code Probate 16000 – Trustees Duties in General
3
California Legislative Information. California Code Probate 15621 – Cotrustees
4
California Legislative Information. California Code Probate 15622 – Cotrustees
5
California Legislative Information. California Code Probate 16226 – Specific Powers of Trustees
6
California Legislative Information. California Code Probate 16228 – Specific Powers of Trustees
7
California Legislative Information. California Code Probate 18100.5 – Certification of Trust
8
California Legislative Information. California Code Probate 17200 – Proceedings Concerning Trusts
9
California Legislative Information. California Code Probate 15642 – Resignation and Removal of Trustees
10
California Legislative Information. California Code Probate 16012 – Trustees Duties in General
11
California Legislative Information. California Code Probate 16402 – Liability for Cotrustee Breach
12
California Legislative Information. California Code Probate 16002 – Trustees Duties in General
13
California Legislative Information. California Code Probate 16004 – Trustees Duties in General
14
California Legislative Information. California Code Probate 16040 – Trustees Standard of Care
15
California Legislative Information. California Code Probate 16003 – Trustees Duties in General