Cal. Penal Code § 1202.46

Notwithstanding Section 1170, when the economic losses of a victim cannot be ascertained at the time of sentencing pursuant to subdivision (f) of Section 1202.4, the court shall retain jurisdiction over a person subject to a restitution order for purposes of imposing or modifying restitution until such time as the losses may be determined. Nothing in this section shall be construed as prohibiting a victim, the district attorney, or a court on its own motion from requesting correction, at any time, of a sentence when the sentence is invalid due to the omission of a restitution order or fine without a finding of compelling and extraordinary reasons pursuant to Section 1202.4.