For true fairness there needs to be a single organization nationally that can collect and process the tax. 50 different filings is an unduly onerous and inefficient hurdle for setting up shop.
Unfortunetly the distrubuted nature of the political system acts aainst this its the same with emplyment having 53 diferent sets of employment laws is very ineficient.
From an outsiders perspective what the USA needs is a proper reform of the constitution and remove a lot of thinkgs from the perview of the individual states.
A maximum age for senators, congessmen and judges would also be a good thing.
Most higher-level politicians are independently wealthy. Lowering congressional pay would just serve to further weed out non-super-affluent candidates. I guess it depends on how you like your politics, so I won't pass judgement either way.
Short term limits means you put more power in the hands of the civil service it takes at least 1 full electoral cycle to understand how it all really works.
https://taxcloud.net/
They calculate and file your returns for you. They get paid a commission directly by the states for facilitating it, so they're free to businesses.