C.R.S. § 38-13-220

(1) On and after October 1, 2002, any amount due and payable as a refund of Colorado income tax or grant for property taxes, rent, or heat or fuel expenses assistance represented by a warrant that has not been presented for payment within six months after the date of issuance of the warrant and that has been forwarded by the department of revenue to the administrator pursuant to section 39-21-108 (5) is presumed abandoned. (2) On and after October 1, 2010, any amount due and payable as a refund of a tax imposed or assessed by the department of revenue that is not addressed in subsection (1) of this section, that is represented by a warrant that has not been presented for payment within six months after the date of issuance of the warrant, and that has been forwarded by the department to the administrator pursuant to section 39-21-108 (7) is presumed abandoned.