Related Information
Question: Am I required to attach the federal return when filing my Colorado income tax return?
The Colorado Department of Revenue does not require taxpayers to attach a copy of the federal return to the Colorado return.

At a later date, The Department of Revenue may request a copy of the federal income tax return if additional information is needed in order to adjust or void an assessment that has been issued. It is important to keep copies and records of both federal and state tax filing information whether the filing is electronic or on paper for four years.

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