I have e-filed my Colorado Taxes. It says I need to mail in or e-filed DR 1778 and all applicable receipts. When I go online it ask for a "File for Date". What date do I enter?

For the "File for Date" on the DR 1778 form, you should enter the last day of the tax year you are filing for, which is December 31, 2024 for your 2024 taxes. This date is likely equivalent to the "For tax year date" on the manual form

For additional information see Colorado Department of Revenue's E-Filer Attachment page.