I permanently moved in Sep 2020 from IA to IN after not working in IA at all during 2020 thanks to Covid. Started freelancing in IN in Sept 2020. When I filed my taxes for 2020 and 2021, I just used my old IA address thinking it needed to match my license (which was at my parents address and why I didn't rush to change it) In 2022 I finally got an IN driver's license and that year started using my IN address on my taxes.
I paid IN state taxes every year 2020-current
IA sent a bill this week for $13K in unpaid personal income tax. All I have as proof that I lived here is that I was being paid for a job you can't do remotely (operating a machine), the fact that I opened a local bank account in Sep 2020 (bank mail still sent to my IA address, though), and the fact that I paid Indiana taxes.
If it's not obvious, I realize this is my very stupid mistake and IA is currently totally justified in sending the bill, just trying to figure out what if anything I can do about this.
Typically when you keep a residence in one state and work in another state you need to file two tax returns. The tax paid in one state is then credited to the other state.
I would recommend speaking to an auditor for both states. You probably will need to file an amended return for the state that you owe the 13K and perhaps even the other state but best to speak to them. They usually are very nice and helpful if you are nice to them.
As additional proof of Indiana residence, You likely have a rental agreement in your Indiana locale that shows when you started living in Indiana......or home purchase papers if you bought a place to live.
Even a long list of Credit Card purchases at Indiana stores, over time, show you were living there.
Utility bills for water/electricity help too,
Assuming the $13K tax bill is due to IA taxing the income you earned after your move to IN: instead of guessing as to what IA will accept as proof of your change pf residence, call the number on the notice you received from Iowa, explain the situation, and ask them what they will accept as proof of your move.