If there is no probate, then there is no "executor" under state law. A person named as executor in a California will is only nominated. Only the court can appoint an executor in California.

When there is no executor, then the tax code provides alternate rules for determination of the executor or administrator for tax filing purposes. The person who holds the estate assets, such as the trustee, is usually that person.

Unless there is a no asset probate actually opened, it appears likely that the person to sign the 706 is the trustee and the son should not be identified as executor.

Hope this helps.

Nelson