California Code, Probate Code - PROB § 13503

(a) The surviving spouse or the personal representative, guardian of the estate, or conservator of the estate of the surviving spouse may file an election and agreement to have all or part of the one-half of the community property that belongs to the surviving spouse under Section 100 and the one-half of the quasi-community property that belongs to the surviving spouse under Section 101 transferred by the surviving spouse or the surviving spouse's personal representative, guardian, or conservator to the trustee under the will of the deceased spouse or the trustee of an existing trust identified by the will of the deceased spouse, to be administered and distributed by the trustee.

(b) The election and agreement shall be filed in the proceedings for the administration of the estate of the deceased spouse and before the entry of the order for final distribution in the proceedings.