TT says we have to upload documents to the CO Dept of Revenue (Form DR 1778) but it doesn't say which forms? How do I find out? Have to report sale of home nonresident.

Based on your comment, it is probably the other state tax return that they want. Go ahead and scan through this list and see if anything else looks familiar.

Form DR 1778 is used to attach the following items:

• Other state(s) income tax return(s)
• Enterprise Zone Credit: DR 1366 and any applicable certification forms from the Zone Administrator
• Gross Conservation Easement: DR 1303, DR 1304 and/or DR 1305 and supplemental documentation.
• Aircraft Manufacturer New Employee Credit: DR 0085 and/or DR 0086
• Nonresident Partner, Shareholder or Members Agreement: DR 0107
• Innovative Motor Vehicle Credit: Vehicle registration and the purchase invoice or bill of sale.
• Child Care Contribution Credit: DR 1317
• Claim for refund on behalf of deceased taxpayer: DR 0102, death certificate
• Colorado Source Capital Gain Subtraction: DR 1316
• Job Growth Incentive Tax Credit: Certification letter from the Colorado Economic Development Commission
• Affordable Housing Credit: CHFA certification letter
• Plastic Recycling Credit: Required documentation to substantiate credit (receipts, bills, etc)
• School-to-Career Investment Credit: Certification letter.
• Other documentation for credits/subtractions claimed (mark the Other box below and enter details).