Colorado estate or trust income tax returns are due by the 15th day of the fourth month following the close of the taxable year.
An automatic six-month extension of time to file the Colorado return is allowed for all taxpayers. There is no extension form required. However, an extension of time to file does not mean this is an extension of time to pay the tax. If at least 90 percent of the net tax liability is not paid by the original due date of the return, penalty and interest will be assessed. If 90 percent 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 extension deadline date, only interest on the tax will be assessed.
Use voucher form DR 158-F which is included in the 105 Colorado Fidicuary Income Tax Forms and Instructions Booklet and is available as a single form on our Colorado Estate Tax Forms Web page.