Cal. Rev. & Tax. Code § 12281

Annually, on or before April 1, each insurer subject to the imposition of retaliatory exactions shall file, in duplicate, with the Insurance Commissioner, in accordance with regulations promulgated by him or her, a retaliatory tax return in the form prescribed by the Insurance Commissioner. Annually, on or before June 15th, each insurer subject to the imposition of ocean marine taxes shall amend its retaliatory tax return by filing, in duplicate, with the Insurance Commissioner, an amended ocean marine retaliatory tax return in the form prescribed by the Insurance Commissioner.