DOR Taxation web site

Income Tax Filing Deadline Changed for 2011

Posted: March 30, 2011
The Colorado Department of Revenue has determined that the filing date for income tax returns due in 2011 will be Monday, April 18, 2011 rather than Friday, April 15, 2011. District of Columbia Emancipation Day is a legal holiday for federal tax purposes, and it will be celebrated on April 15 (normally, it is celebrated on April 16).  The Internal Revenue Service will be closed April 15 because it is headquartered in the District of Columbia and the federal income tax deadline is extended to Monday, April 18.  Therefore, the due date for Colorado income tax returns and estimated income tax payments normally due on April 15 will be extended to April 18.  Returns filed on Monday, April 18 will be considered as timely filed.  However, note that returns filed on Tuesday, April 19 will be considered four days late.

This revised deadline applies only to 2010 income tax returns and estimated income tax payments (the first quarter payment for 2011) due on April 15, 2011.  Colorado taxpayers generally need to complete a federal tax return before completing the Colorado tax return and an extended federal deadline might cause confusion about when federal and Colorado returns are due.  Therefore, the Colorado Department of Revenue is extending the state deadline this coming year to match the federal deadline of April 18.

Refer to Colorado Department of Revenue Regulation 39-22-608.


Taxpayers are encouraged to file their return electronically online with Colorado NetFile or through federal/state e-file software.  Corporations and partnerships may also file through federal/state e-file software.


Income tax payments for tax year 2010 and estimated payments for tax year 2011 may be made through the Colorado Online Payment service.