California Code, Probate Code - PROB § 2329

(a) If a guardian or conservator moves the court for reduction in the amount of the bond, the motion shall include an affidavit setting forth the condition of the estate.

(b) Except upon a showing of good cause, the amount of the bond shall not be reduced below the amount determined pursuant to Section 2320.

(c) Nothing in this section limits the authority of the court to reduce the amount of the bond with or without notice under Section 2328.