Colo. Rev. Stat. § 15-12-604
If bond is required and the provisions of the will or order do not specify the amount, unless stated in his application or petition, the person qualifying shall file a statement under oath with the registrar indicating his best estimate of the value of the personal estate of the decedent and of the income expected from the personal and real estate during the next year, and he shall execute and file a bond with the registrar, or give other suitable security, in an amount not less than the estimate. The registrar shall determine that the bond is duly executed by a corporate surety, or one or more individual sureties whose performance is secured by pledge of personal property, mortgage on real property, or other adequate security. If the personal representative be a company or association with capital and surplus at least equal to that required by law of a corporate surety, the registrar may excuse a requirement of bond. The registrar may permit the amount of the bond to be reduced by the value of assets of the estate deposited with a domestic financial institution (as defined in section 15-15-201 ) whose deposits are insured to the satisfaction of the court in a manner that prevents their unauthorized disposition. On petition of the personal representative or another interested person, the court may excuse a requirement of bond, increase or reduce the amount of the bond, release sureties, or permit the substitution of another bond with the same or different sureties.
C.R.S. § 15-12-604