According to Colorado Department of Revenue, "Colorado income tax returns are due to be filed three and one-half months after the close of the tax year. An automatic six-month extension of time for filing the Colorado corporation income tax return is allowed for all taxpayers."
If at least 90% of the net tax liability is not paid by the original due date of the return, penalty and interest will be assessed. If 90% or more of the net tax liability is paid by the original due date of the return and the balance is paid when the return is filed by the last day of the extension period, only interest will be assessed.
Form DR 158-C is to be used to make whatever payment must be made by the original due date of the return to meet the 90% requirement.
If after the original due date of the return it is found that the amount paid is insufficient to meet the 90% requirement, additional payment should be made as soon as possible to reduce further accumulation of penalty and interest. Make such payment on form 158-C.
Please note that a "federal extension of time for filing will not be accepted for Colorado purposes."
Taxpayers are required to submit Form DR 158-C with payment to:
Colorado Department of Revenue,
Denver, Colorado 80261-0008.
You can click the following link below to access the DR 158-C form.
http://www.colorado.gov/cs/Satellite...&ssbinary=true
Filing extension for a C Corp in Colorado 
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