Original returns

Every resident individual and every nonresident individual with income from Colorado sources is required to file a Colorado Individual Income Tax Return (DR 0104) if either:

the individual is required to file a federal income tax return; or

the individual has incurred a Colorado tax liability for the tax year.

The requirement to file also applies to any part-year resident who is either required to file a federal income tax return or has incurred a Colorado tax liability for the tax year.

Income tax returns for calendar year filers are due April 15th of the next year. All individual income taxpayers are allowed an automatic six-month extension for filing of their income tax returns. If either the regular or extended due date falls on a Saturday, Sunday, or legal holiday, the due date will be extended to the next business day.

If an individual fails or refuses to file any required return, the executive director of the Department may file a return on the individual’s behalf with such information as may be available. The assessment of tax based on the executive director’s filing is as good and sufficient as an assessment based on a return filed by a taxpayer.