California Revenue & Taxation Code
Cal. Rev. & Tax. Code § 5011
Official textleginfo.legislature.ca.gov
All or any portion of any assessment of state-assessed property heretofore or hereafter levied may, on satisfactory proof, be canceled by the board if it was made:
# (a)
More than once.
# (b)
Erroneously or illegally.
# (c)
On improvements when the improvements did not exist on the lien date.
Source: view the official text