If I earned commission income in 2019 from work I did in 2018 in CO But was a full time resident of CA all of 2019. Who do I pay taxes to? CO took out and CA also wants

[Hal_Al]

Both. 

AS a current year CA resident, all your income is reportable and taxable. CA will give you a credit or partial credit for any tax you pay CO. 

There may be some question as to whether CO can tax you, but  your employer thinks they can, so he took out CO withholding.

You will need to file a CO non resident return.  I suggest you call CO tax dept and explain the situation, to see if you file for a refund of all the withholding or a regular non resident return.

[RobertG]

When you earn money in more than one State, you usually have to file in both States.

Each State does it differently, but all states take your tax payments to other States into account, so you will not be taxed twice on the same income.

1. When you are filling out the personal information section, you will be asked Did you make money in any other States?
2. Answer Yes to that question and make sure your nonresident state(s) are selected from the drop-down.
3. After you finish your federal return, you'll automatically move to the State tab, where you'll see your nonresident state(s) listed in addition to your resident state.

To ensure accurate calculations, we strongly recommend preparing your nonresident state return before you prepare any resident or part-year state returns.

See the TurboTax website:How do I file a nonresident state return? for further information.