Cal. Rev. & Tax. Code § 5763

A delinquent penalty of 6 percent shall attach at 5 p.m. on the day any tax imposed by this part becomes delinquent. An additional penalty of 1 percent shall attach to the tax on the first day of the first calendar month commencing after the tax becomes delinquent and on the first day of each calendar month thereafter, until the delinquent tax and penalties have been paid in full.