We are MI residents. My husband works in ND 20 days a month. So he stays out there 20 days and is home 10. The kids and I are in MI full time. How do we file our states? Can we file dual residency? It wants us to put dates in that we moved. I can't put every date in that he comes home. He has a MI driver license an stays in company housing.
You didn't move and you both were residents of MI for the entire year. File a resident return for MI and a non-resident return for his SD income.
When both of you complete the My Info Personal Interview:
Select Michigan as your state of residence;
Answer "No" when asked if you "Lived in another state in 2020?" That question only applies if you changed your state of residence in 2020.
When asked if you "Earned money in another state?", answer "Yes" (because your husband works in SD 20 days of the month).
Both MI and SD will tax your husband's SD income - MI because he is a resident and SD because he earned it there. MI, however, will give him a credit (against MI tax) for whatever tax he has to pay SD on the same income. This is how states avoid "double-taxation".
Prepare the SD return first - this is how MI will be able to know how much of a tax credit he will get against his MI taxes on the SD income.
It comes out saying that ND owes us about $500 and that we owe MI over $3k. Would that be right with him staying in ND more than MI?
It could be correct, depending on what other income your family has and how much tax was withheld for both ND and MI.
The amount you "owe" depends on your state tax liabilities and what state tax payments (e.g. withholding) were made throughout the year.
Without knowing your MI and ND taxable incomes and the state taxes withheld for both, it would be impossible to say whether the figures you gave would be correct.