Q What are my options to discuss with my company payroll department?
A. Say thank you, for finally getting it right after 20 years.
The general rule is: your report all your income on your home state return, even the income earned out of state. You file a non-resident state return for the state you worked in and pay tax to that state. Your home state will give you a credit, or partial credit, for what you paid the non-resident state.
When you worked in a state without an income tax (e.g. Texas ), there will be no credit, since there was no TX tax. In other words, having worked in a state without an income tax does not get you out of paying state tax on that income, to your home state.
It sounds like you may need to file 20 years worth of back taxes for MO.
