If I moved to Missouri, but my job for the whole year was in Kansas, do all of my earnings count as income earned in Kansas?

Q. Do all of my earnings count as income earned in Kansas?

A. Yes.  

But the income, received after the move is taxed by both KS & MO.  The general rule is: your report all your income on your home state return, even the income earned out of state. You file a non-resident (part year resident, in your case) state return for the state you worked in and pay tax to that state. Your home state will give you a credit, or partial credit, for what you paid the non-resident state. You will have to file a part year resident KS state return and pay KS tax on the income earned there, both while a resident and while a non resident. You will also file a MO part year resident return and calculate tax on the income earned after the move. MO will give you a credit, or partial credit, for the tax you pay KS, but only on the income after the move.  So, there will be little or no double taxation. Do the KS state return first (to facilitate the calculation of the MO credit). 

You would file part-year resident return for Kansas and Missouri. 

All your Income is taxable on your Kansas return. It is income from Kansas sources.

On you Missouri return, only income earned while living in Missouri is taxable. However, as a Missouri resident with income from another state, you may be able to claim a credit for tax paid to that state.

How do I file a part-year state return?