Amended returns for federal adjustments

An individual is required to file an Amended Colorado Individual Income Tax Return (DR 0104X) to report any change to an item or amount determined under the Internal Revenue Code that is used to compute Colorado income tax. An amended Colorado return is required regardless of whether the federal adjustment results from and audit or other action by the IRS or from the timely filing of an amended federal return or federal refund claim.

The amended Colorado return is due within 180 days after the federal adjustment is finalized. If a taxpayer files an amended federal return or a federal refund claim, the due date is 180 days after the amended federal return or refund claim was filed. If the federal adjustment arises from an IRS audit or action, the amended Colorado return is due 180 days after all federal adjustments arising from the IRS audit or action have been finally determined. In general, federal adjustments are finalized for Colorado income tax purposes when all rights to appeal the federal adjustment have been waived or exhausted or the taxpayer and IRS both sign an agreement with respect to the adjustment.

Please see Part 9 of this publication for additional information regarding the period allowed for assessment.