We give you an automatic 6-month extension to file your return. You may file Form 1040, Form 1040A or Form 1040EZ any time before the six-month extension period ends.You must make a proper estimate of your tax for the year. How to file form FTB 3519. You can get an automatic 6-month State of California tax extension and have until October 15 to file your return. To request an extension, you'll need to submit IRS Tax Form 4868 before April 15 (July 15 in 2020). This gives you until October 15 to file without penalties. The California tax deadline extension covers tax filing and payment deadlines initially falling between January 21, 2024, and June 17, 2024. To get an automatic extension, fill out Form 4868. This one-page document asks for basic information such as your name, address and Social Security number.