TurboTax software for 2018 is no longer available, nor would it be supported or updated even if you can find it on eBay, etc. And...you cannot use TT to prepare a "stand alone" state return for any tax year. When you use TurboTax, your information flows from the federal software to the state software. Your reasons to file a 2018 state return are puzzling and you do not mention who advised you to do so, but if you really need to prepare a return for 2018 for CO, seek local paid tax help.
**Disclaimer: Every effort has been made to offer the most correct information possible. The poster disclaims any legal responsibility for the accuracy of the information that is contained in this post.**
