Long ago, DW was a traveling nurse, licensed in three states; our "home" state of Montana, Washington State, and California.
Of course, the Federal IRS wanted ALL income reported, no matter what state it was earned in.
Montana also wanted all income reported on the Montana Income Tax Return.
Washington has no income tax, so no problem there, we just paid the sales tax on everything we bought that was taxable.
California wanted all income earned in CA reported on the income tax forms, Plus we had to pay the CA sales taxes.
So, every year, we had to file Federal tax forms, Montana tax forms, AND California tax forms. It wasn't all that difficult, but the paperwork was annoying.
If we had moved to Wyoming instead of maintaining our Montana residence, that would have eliminated one set of tax forms. At the time, we didn't think it was worth the trouble.