State tax filing

You will be able to utilize your 2018 AMT Credit Carryover from California if you had an AMT credit carryover from 2018 or if you paid AMT in 2018.

Based upon the information provided in your question, you will be able to claim the credit.  

To do this, go into your state interview section for California again.  Select Credits and taxes.

Continue through the screens until you see the question regarding AMT.  If you don't see the following screen, scroll down on the screen with all the credits until you see Taxes.  Select Alternative Minimum Tax.

Continue until you see the following screen.  Be sure to enter your CA AMT credit carryfoward here.  This will ensure you get credit in 2019 for the carryover from 2018.