You can apply online for any of these exemptions through the Cook County Assessor's Office. 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.Homeowners' Exemption. Exemption on a residence that is both owned and occupied as the principal place of residence. Download PDF BOE-266 REV. Each year applicants must complete and file Form PTAX-340 with the Chief County Assessment Officer. San Bernardino County offers several property tax exemption programs designed to reduce the financial burden on homeowners. To claim the exemption, the homeowner must make a one-time filing with the county assessor where the property is located. One place to search and find your next commercial real estate rental.