@Arthur9199
Be careful here....,...when the software asks for your resident state (NOT your mailing address), you put in your HOR state....or your state of legal residence state (SLR), if you changed your SLR legally by filing a DD 2058 with the military.
Yoru posting in South Korea is just your Mailing address, not your residence state...which probably remains as MO (if you've never submitted a DD2058 with the military)
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Read:
What is my military state of residence?
____________*Answers are correct to the best of my knowledge when posted, but should not be considered to be legal or official tax advice.*