Probate Code § 20220

(a) The trustee or any transferee may commence a proceeding to have a court determine the proration pursuant to this chapter.

(b) A proceeding under this article shall be commenced in the court in which the estate of the decedent was administered or, if no administration proceedings have been commenced, in the superior court of any county in which the estate of the decedent may be administered.

(c) If proceedings for the administration of the decedent’s estate are pending, a proceeding under this article shall be combined with the administration proceedings. If a proceeding is commenced at any time before final distribution, there shall be no additional filing fee.