CA Prob Code Section 9705

(a)

Subject to subdivision (b), where a trust company is a personal representative and in the exercise of reasonable judgment deposits money of the estate in an account in any department of the corporation or association of which it is a part, it is chargeable with interest thereon at the rate of interest prevailing among banks of the locality on such deposits.

(b)

Where it is to the advantage of the estate, the amount of cash that is reasonably necessary for orderly administration of the estate may be deposited in a checking account that does not earn interest which is maintained in a department of the corporation or association of which the trust company is a part.