Cal. Code Regs. tit. 18 § 15681
If a donor's return is not filed on or before the date on which it is required to be filed (see Section 15651.2 and Revenue and Taxation Code Sections 15651 and 15652), or if a donor's return does not show every taxable transfer made during the reporting period for which it is filed, a penalty is added to any tax due on the transfers not returned in an amount equal to 5 percent of such tax. An additional penalty of 25 percent of the amount of such tax is added thereto if the failure to file the return or include any transfer therein was the result of a fraudulent intent to evade the tax.
The penalties specified in this regulation are not only added to the amount of tax due, but become a part of such tax for the purpose of determining interest on delinquent tax payments. Any deficiency determination issued (see Section 15801) will contain a statement of the amount of penalties, if any, specified in this regulation for which the taxpayer is liable.
If an extension of time for filing a return is granted (see Section 15651.2 and Revenue and Taxation Code Section 15652) the penalties specified in this regulation will not be imposed unless the taxpayer fails to file a return on or before the expiration of the period of extension, or, having filed a return before such date, fails to report every taxable transfer.
Even though an extension of time for filing a return is granted, the tax becomes delinquent and subject to interest at 7 percent per annum from the original due date until paid. The granting of an extension of time operates to relieve the taxpayer from penalty for late filing of the return but not from the payment of interest. (See Revenue and Taxation Code Section 15962).
NOTE: Reference: Section 15681, Revenue and Taxation Code.
Cal. Code Regs. Tit. 18, § 15681