A method of taxation using a fixed proportion of property value; for example, real estate taxes collected at the rate of a specific dollar amount of appraised value or assessment. People use the ad valorem method as a formula to decide how much tax to pay the government. A commonly used formula for computing taxes is as follows (assumptions: properties are assessed at 25\% of valuation, appraisal is $100,000 and the tax rate is $7.50 per $100): $100,000 x 25\% = $25,000 1?2 $100 = 250 ($100 units), 250 x $7.50 = $1,875 1?2 12 (12 months) = $156.25 per month