Tax Extension Deadline 2024 Form California. When are small business taxes due in california? For the 2023 tax year, key dates include the main filing deadline and deadlines for estimated tax payments, typically due on april 15th, june 15th, september 15th, and january 15th of the following year.

As a result, affected individuals and businesses will have until june 17, 2024, to file returns and pay any taxes that were originally due during this period. For the 2023 tax year, filed in 2024, llcs filing as sole proprietors must submit form 1040 by april 15 without an extension.