Well, that depends on what the State of MO is asking you to do. We can't see what MO had a problem with.
Generally, If you agree with their changes or assignments of $$, then you just pay them....BUT, if they are actually asking you to verify your income assigned as MO-source income, you may have to either send them proof (if they asked for it in their letter), or amend your MO tax return to make whatever changes are necessary...if any.
The income % stuff is only used for MO non-residents working in MO, or for part-year MO residents who either moved into, or out of MO during 2020, and are choosing to file as a non-resident for the year.
You were supposed to indicate what sub-$$ amounts of gross Federal income values were to be considered MO-sourced income during the MO Nonresident/Part-year interview. Those #'s are used to calculate the % of total income that MO will end up taxing. Now, if you did not enter the proper $$ that should be subject to MO taxation on the form MO-NRI, then you need to review the printout of your existing MO-NRI to see if you agree with whatever MO has a problem with....and amend your MO tax return if they want that to be done with any corrections you are making. But you re going to have to read that notification from MO closely...we can't see it nor know what it says.
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Note: I'm not a MO tax expert, and can only reply as to what I suspect is the issue, given what limited info you posted.
AND.....DOES THIS HAVE SOEMTHING TO DO WITH UNEMPLOYMENT INCOME?
If you had unemployment income during 2020, filed your taxes before the unemployment exemption changes were enacted and MO is now making changes relative to all the crazy late legislation relative to that, I'm not sure anyone in this forum knows the mess that might create with your tax file. Again, the letter form MO, that we can't see, should be telling you what they want to be done. If their notice was actually letting you know that they were reducing your MO-sourced income due to that change, then you may not have to do anything.
Sorry I can' be more help.
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____________*Answers are correct to the best of my knowledge when posted, but should not be considered to be legal or official tax advice.*
