On the following February 15. Before the 30th day following the date of notice of supplemental assessment, whichever comes first.Legal deadline to file timely exemption claims for homeowner, veteran, disabled veteran, cemetery, church, college, and welfare exemptions. Applications and further details for this program are available on the State Controller's Property tax postponement web page. Welcome to the homestead estimated amount page for Single Family Detached homes for Santa Clara county. Information needed to complete each form section. Any deadlines associated with each form filling timeline if a deadline exists. As April 15th approaches please file your rendition early to avoid delays in processing. We strive to promptly and thoroughly address your inquiries. In fact, the earliest known record of property taxes dates back to the 6th century B.C. In the U.S., property taxes predate even income taxes.