Arkansas does not tax military retired pay. Your military pension is fully exempt from Arkansas income tax. Thrift Savings Plan money is separate: TSP does not withhold state or local tax, but distributions are reported on IRS Form 1099-R and are subject to state tax, and early distributions can be taxed at a higher rate.
There is nothing to apply for. Leave your military retired pay out of the income you report on your Arkansas return.
Your Form 1099-R showing the retired pay, kept with your tax records.
