Commingle means to mix the funds belonging to one party with those of another party. The funds involved are usually held in trust for another, such as funds held for a client or beneficiary. Spouses are allowed to commingle funds by putting money in joint accounts, but may risk turning separate property into community property by doing so. Business partners may legally commingle funds, but a business partner may have to account to the other.
Fiduciaries, such as trustees, guardians or lawyers, holding client funds must avoid the conflict of interest that can be found by the commingling of those funds with their own. To avoid commingling, trustees, lawyers, guardians and those responsible for another's funds set up trust accounts so that the funds are kept separately and any interest earned may be accounted for.
