When is California State Income Tax due?

The due date for CA state tax for 2020 was on May 17, 2021---the same deadline as the federal deadline.

You must pay your state tax due using the state’s preferred method of receiving payment.  For most states that will be by making a payment to the state’s own tax website, or by mailing a check or money order.

https://ttlc.intuit.com/questions/1900884-what-are-my-options-for-getting-my-state-refund-or-for-paying-any-state-taxes-i-owe

https://ttlc.intuit.com/questions/1901670-how-do-i-contact-my-state-department-of-revenue