Pinochet said:
It's usually an amount of income, not a number of days. California's website says the threshold was $19k of CA income for a single person in 2021. That's just the income earned in the state, not all of your income everywhere. The oddity is that whether or not you owe tax or need to file a return, your employer may have a withholding and reporting requirement.
Plenty of consultants have dealt with this for years, and it's just a fact of life. You have a few dollars of tax withheld in various states and just pass on filing a return to get $12 back. Some companies will gross you up to pay your tax, but not all. Price of working for a big company and traveling to different places.
Yep, when I was in Management Consulting, my record number of state returns in a year was definitely in the double digits. Even had to file in a few local city/county jurisdictions. Thankfully my firm at the time grossed up and withheld based on my total income. So when I apportioned it and filed at the end of the year I got a return back from most of those states ranging from a few bucks to a thousand or so.
And since these were grossed up and weren't actually withheld out of my check, it was a nice little additional bonus at the beginning of the year that was typically $2-3k in total.