The starting point for the Missouri state tax return is the Federal Adjusted Gross Income. If you were able to deduct any student loan interest on your Federal return, the deduction would have been taken into account prior to the calculation of the AGI.
There would have to be a separate entry on the Missouri return to adjust for student loan interest for cases where it was not deductible on the Federal return. I did not find such an entry. Therefore, if you cannot deduct the student loan interest on your Federal return, you will not be able to deduct it on your state return either.
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