Tax deductions subtract a certain amount from the property's assessed value to arrive at the net assessed value. For example, let's say you own a home assessed at $180,000 and you qualify for the homestead deduction. Your standard homestead deduction is $45,000, and your supplemental deduction is $47,250. Without any deduction, the tax rate would be applied to the AV of $180,000. But with the homestead deduction, the tax bill is calculated based on a net AV of $87,750.