If you worked for the same employer in both states you will need a W-2 that correctly shows the wages earned in each jurisdiction.  If it was different employers you will need a W-2 from each. 

You will also need to report wages in both states showing each state as a part-time resident.  You start with your state of residence and employer as of 12/31/19 and work backward toward the beginning of the year.

If you did not inform the payroll department of whoever you work for of a change in your resident state, they had no reason to withhold taxes for your new state. You will still enter your W-2 "EXACTLY" as printed, because it is "IN FACT" correct as printed. They can't change your W-2 because it's not wrong. Your employer did "IN FACAT" withhold *AND* pay state taxes to MN for the year.

The important thing here is, you will be completing a part-year resident tax return for both states. It is *IMPORTANT* that you complete the state tax return for your *OLD* resident state *FIRST*. Then you do the return for your new resident state last. Both state returns will be a part-year resident return.

In the end, the program, based on *YOUR* import, will take care of splitting your tax liability between the two states. So don't be surprised to find that you are getting a refund from MN, and will owe that refunded amount (more or less) to CO since absolutely no taxes were withheld from your paychecks for CO.