Cal. Code Regs. tit. 18 § 13987
Except as otherwise indicated in this regulation and Section 13987.1, any tax or assessment levied by the State of California, or by any county, city and county, city, or district thereof, is allowable as a deduction from the market value of the property, if it was a lien at the date of decedent's death against property included in any transfer subject to the Inheritance Tax Law made by the decedent.
Interest on such a tax which accrued prior to the date of death is also deductible, but interest which accrues on or after the date of death is not deductible.
A tax on property situated outside the State of California or on any other property which is not subject to the Inheritance Tax Law is not deductible.
NOTE: As to the deduction of a tax which is not a lien at the date of decedent's death against property included in any transfer subject to the Inheritance Tax Law, see Section 13983.
NOTE: Reference: Section 13987, Revenue and Taxation Code.
Cal. Code Regs. Tit. 18, § 13987