California Revenue & Taxation Code
Cal. Rev. & Tax. Code § 5096
Any taxes paid before or after delinquency shall be refunded if they were:
# (a)
Paid more than once.
# (b)
Erroneously or illegally collected.
# (c)
Illegally assessed or levied.
# (d)
Paid on an assessment in excess of the ratio of assessed value to the full value of the property as provided in Section 401 by reason of the assessor’s clerical error or excessive or improper assessments attributable to erroneous property information supplied by the assessee.
# (e)
Paid on an assessment of improvements when the improvements did not exist on the lien date.
# (f)
Paid on an assessment in excess of the value of the property as determined pursuant to Section 1614 by the county assessment appeals board.
# (g)
Paid on an assessment in excess of the value of the property as determined by the assessor pursuant to Section 469.
Source: view the official text