To claim the exemption, the homeowner must make a one-time filing with the county assessor where the property is located. All homeowners automatically have a homeowner's exemption, which protects part of their equity from involuntary sales (foreclosures).Complete form BOE-266, Claim for Homeowners'. Property Tax Exemption. You may upload documentation to prove your claim. Have the tax bill in front of you, as it contains information necessary to complete the E-Form. Download PDF BOE-266 REV. Welcome to the Alameda County Treasurer-Tax Collector's website. Our staff has worked hard to provide you with online services that provide useful information. To qualify for the homeowners' exemption, the home must have been the principal residence of the owner as of January 1 of that tax year.