Remote Work + A Residential Move

[DonQ]

Which states require filing of taxes, and in what order and manner (resident, non-resident, part-year, etc.) should they be filed in the following scenario?
Spouse 1 - Worked in South Carolina, lived in North Carolina part year, then moved to Missouri remainder of year

Spouse 2 - Worked in Missouri, lived in North Carolina part year, then moved to Missouri remainder of year

Which should be the first state to which a return should be filed and in what manner?  By my count, there should be 3 state returns filed here, but only two states should receive income tax payments.  Is this correct?  Any help would be appreciated.  Remote work is complicated enough, but moving just adds another layer of complexity.

[MayaD]

If you lived in Missouri and North Carolina, you need to file Part year resident resident return for each of those states and allocate your income between NC and MO. 

How do I allocate (split) income for a part-year state return?

You also need to file non-resident return for SC. As a nonresident, you are generally required to file a South Carolina return if you work in South Carolina or are receiving income from rental property, businesses, or other investments in South Carolina. sc.gov

How do I file a nonresident state return?

[DonQ]

Would the full-year income need to be reported to South Carolina in a non-resident tax return, even though taxes were only paid to South Carolina during the time Spouse 1 lived in North Carolina?  Once the mid-year move to Missouri was complete, the South Carolina company took Missouri taxes out via payroll.

[AmyC]

There is no reciprocal agreement between any of the states you listed. This means: 

SC gets a nonresident tax return with the SC wages from working in SC only. SC will not tax the SC source income that was earned in MO.

NC gets a part-year return that will include the SC wages and a SC tax credit  plus NC is entitled to a portion of the MO income earned while living there.

MO as a part year resident, you want to file as a resident in order to claim the credit for tax paid to NC on the MO income claimed there. See page 5 of  MO-1040 Instructions 

Determine SC, then NC and finally MO in that order. Pay attention to the NC tax with only the SC income vs with the MO income. The difference is what you will put on the MO tax credit form. 

You could owe taxes to any of the 3 states, particularly NC. State credits are given based on the lower of tax between the states. It doesn't sound like any NC tax was paid so I would expect a bill there.