California Revenue & Taxation Code
Cal. Rev. & Tax. Code § 6381
Official textleginfo.legislature.ca.gov
There are exempted from the computation of the amount of the sales tax the gross receipts from the sale of any tangible personal property to:
# (a)
The United States, its unincorporated agencies and instrumentalities;
# (b)
Any incorporated agency or instrumentality of the United States wholly owned by the United States or by a corporation wholly owned by the United States;
# (c)
The American National Red Cross, its chapters and branches.
Source: view the official text