the tax law was found to be invalid by a court, so all taxes paid under the law had to revert to the rate paid under the previous law. However, only taxes paid in the last four years are subject to court rulings like this due to statutes of limitation, which is why the CFTB went back four years, and not zero (everyone paying after the law was found to be invalid would have a 14th amendment suit since the law is invalid), three (see previous) or five (statute of limitations).

> the tax law was found to be invalid by a court

This isn't quite true, only part of the law was found to be unconstitutional (the part requiring that 80% of your payroll be located in CA). The FTB could have chose to continue the law but would have to retroactively pay people who previously applied for this deduction and were refused because they had >20% payroll outside of CA.

Okay, thanks for the info!

Scary! Which part of my net money belongs to me? Do we have to tt money to the caiman AFTER paying taxes now?

Constitutionality of law indicates otherwise.

>The whole retroactive thing strikes me as incredibly wrong and should be illegal.

if you want to make duly passed state laws like this illegal, you would need to take a time machine back to May of 1787 and try to add "no ex post facto law shall be passed" to the constitution.

if you do can I come with you just to see the look on your face?

I guess my joke didn't come across. The Constitution already has the words "no ex post facto law shall be passed" in it (my joke is that all that work going back to try to add it would be wasted) right after the words that congress can't just declare someone guilty of a crime without a trial. Just Google "no ex post facto shall be passed."