DOR Taxation web site


Expect to get a refund this year but can't make the deadline?
You can take advantage of the state's automatic six-month extension of time to file and file your state form on or before October 15. There is no form to fill out and no need to notify the department. The extension applies to filing the Colorado tax form 104, not to any state income tax you may owe.

Owe state income tax this year?
90% of your tax liability must be paid on or before April 15 to avoid penalties. Any remaining balance due would be subject to interest only. 

Can installment payments be made?
Yes. File your income tax return by April 15 and include on the paper or electronic return the amount you owe. Pay as much as you can of the amount you owe by the filing deadline.
Once your billing information is in our computer system you may set up an agreement to pay. There are two methods of setting up an installment plan.

  1. Sign up to access your account in Revenue Online and request a payment plan, or
  2. Contact our Call Center at (303) 238-7378.

If you want to start making payments on your account prior to receiving a bill, you can make a payment online through Revenue Online. Make sure you use the primary Social Security number and the tax year to which the payment applies.


What if I'm living or traveling abroad or serving in the military on the filing deadline?
If a person is out of the country on April 15, the deadline for filing the state return and paying any tax owed plus interest is June 15. However, if you need more time to file, you may file by the October 15 extension deadline but interest and penalty will apply.

Colorado law allows military and support personnel stationed in a combat zone as declared by the president to postpone filing and paying state income taxes until 180 days after their assignment in the combat zone ends. Interest and penalty are deferred during this period. Because most Colorado taxpayers receive a refund, affected taxpayers may want to authorize someone else to file their return for them via a Power of Attorney (DR 0145).  The Department of Revenue will also accept a copy of the federal 2848 Power of Attorney declaration.

Penalty and interest charges on tax owed
When at least 90 percent of the tax owed is paid by the April 15 deadline, taxpayers are charged interest only and avoid penalty charges as long as the income tax filing (electronic or paper) and balance owed are sent by the October 15 extension deadline. 

  • The interest rate for each calendar year is three points over the prime rate as of July 1 of the prior year. The additional three points will be waived.
  • If the payment is 90% or more of the amount owed you will be charged interest only on the remaining percent, no penalty as long as the return and balance owed are sent by the October 15 extension deadline.
  • The 90% amount applies to corporations as well as individuals.  Corporations use the Payment Voucher for Automatic Colorado Extension for Corporations (DR 158-C) to make their payment.

Penalty and interest rates 

  • Interest rate for each calendar year is determined in July of the prior year and is based on the prime rate.  A discounted rate which is 3 percentage points lower than the prime rate is available if the balance due is paid when the return is filed or within 30 days.  For a listing of rates for each calendar year, see publication  Publication FYI General 11, Colorado Civil Tax Penalties and Interest.
  • Penalty is 5 percent of the balance due for the first month past the April 15 deadline plus 0.5 percent for each additional month up to a maximum of 12%.