California offers the typical international option: they'll send you your estimated annual taxes, and you just jave to correct them if there's a discrepancy. This was supposed to be the default option for Californian state taxes. Instead, Intuit's army of lobbyists managed to almost get rid of it. It is now an opt in for people that is not advertised or easy to find on the gov website. Intuit's business model is making tax preparation easier. If tax preparation wasn't so deliberately complicated in the US, they would no longer have a viable business model.