1) The MT part-year should work OK if you did go thru the MT part-year allocation questions. The tax should be chopped down based on what approx. fraction of income you indicated was MT income (thru July). Print out your forms, and see what is in the Part-Year allocation forms for MT to see if it is approx correct.
2) MO is a different issue. MO is one of a few states that do part-year a bit strangely (my opinion) and I don't know what choices TTX gives you, or which way would be better.
MO tells part-year residents to either: a) File a full-year MO resident tax return for MO...where MO calculates a tax on everything, and then allows you to take a credit for the tax you had to pay MT on the MT part-year tax return. This may be what you are seeing in your MO forms, but you might have to print them out to be sure...OR... b) File a full-year non-resident tax return for MO, where you indicate all wages, dividends, interest, cap gains, i.e. all income only from your July move date to the end of the year as MO nonresident income, and calculates a tax on that. Since this specifically targets only the last half of the year, there is no credit for taxes paid to MT ...since MT didn't tax anything after July (if done right).
____________*Answers are correct to the best of my knowledge when posted, but should not be considered to be legal or official tax advice.*
