Dual Resident Trust Credit.
Regulation 39-22-108.5

(1) 	Limitations.
(a) 	A taxpayer can not claim both the dual resident trust credit and the credit for tax paid to another state (§39-22-108, C.R.S.) in the same tax year. If a taxpayer qualifies for both credits in the same tax year, the taxpayer shall elect which credit will be claimed on the return.
(b) 	The credit is not available to a trust that became a Colorado resident trust prior to May 26, 2006.
(c) 	The credit is available for tax years beginning on or after January 1, 2006.
(d) 	Any excess credit is not refundable and may not be carried forward or back to another tax year.
 (2) 	Documentation.
(a)	A taxpayer claiming a dual resident trust credit shall file a copy of the income tax return from the other state(s) with the Department of Revenue at the time of filing the tax return claiming the credit. 
(b)	A taxpayer who electronically files the Colorado income tax return must include requested information from the other state’s tax return and submit a written copy of the same to the Department of Revenue upon request. 
(c) 	Documentation to support the tax return from another state must also be submitted to the Department of Revenue upon request.