How property tax assessments work

Market value on a valuation date

Every state values property as of a set date, most often January 1: Texas appraises at market value as of January 1 (Tex. Tax Code §23.01), Washington values as of January 1 (RCW 84.40.020), and Minnesota as of January 2 (Minn. Stat. §273.01). Sales and market changes after that date do not count for that year.

Assessors value thousands of homes at once with mass-appraisal models built from recent sales and the property records they hold: size, age, quality, lot and location. A model can be right for a neighborhood and still wrong for one house, which is why every state lets owners appeal.

From market value to assessed value

Some states assess at full market value: Texas at 100% (§23.01) and Washington at 100% of true and fair value (RCW 84.40.030). Others assess at a fixed share: Georgia at 40% of fair market value, Ohio at 35% of true value (ORC 5715.01), and Illinois at 33⅓% outside Cook County (35 ILCS 200/9-145), with Cook residential property at 10%. Pennsylvania counties keep values from their last reassessment and the state publishes a common level ratio for each county.

The ratio matters when you compare your assessment with sale prices. See what an assessment ratio is.

Caps and exemptions

Many states limit how fast a home’s taxable value can rise: 10% a year for a Texas homestead (§23.23), 3% or inflation for a Florida homestead (Fla. Stat. §193.155), 2% a year from the base year in California (Rev. & Tax. Code §51), and the lesser of 5% or inflation in Michigan (MCL 211.27a). Exemptions such as a homestead exemption then subtract from the taxable value. See homestead caps and assessment limits.

From taxable value to the bill

Each taxing unit (county, city, school district, special districts) sets a rate, and your bill is the taxable value times the combined rate. An appeal changes the value, never the rate; the rate is set in public budget hearings.

• Market value on the valuation date
• × the assessment ratio (100% in some states)
• → assessed value, then any cap and exemptions
• → taxable value × combined tax rate = your bill

Where an appeal fits

An appeal asks the assessor, then an independent board, to lower the value for that year. It is time-limited: most states give 25 to 90 days after the notice, and a few use fixed dates. See appeal deadlines by state. Every state’s first-level board, deadline rule and notice labels are on the state pages.

Check whether yours is over-assessed

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Related guides

• How to read your property tax assessment notice
• What is an assessment ratio?
• Homestead caps and assessment limits: why taxable value can sit below market

1. Tex. Tax Code ch. 23, appraisal methods (§23.01 market value, §23.23 homestead limit)
2. RCW 84.40.020, January 1 valuation date
3. RCW 84.40.030, 100% of true and fair value
4. Minn. Stat. §273.01, January 2 assessment date
5. Georgia DOR, property tax FAQ (40% of fair market value; 45 days to appeal)
6. Ohio Rev. Code 5715.01, taxable value not over 35% of true value
7. 35 ILCS 200/9-145, 33⅓% statutory level of assessment
8. Cook County Assessor, your assessment notice and tax bill (residential at 10%)
9. Pennsylvania STEB, common level ratio certification (18 Jun 2025)
10. Fla. Stat. §193.155, homestead assessment limit
11. Cal. Rev. & Tax. Code §51, base year value and the 2% inflation factor
12. MCL 211.27a, taxable value cap and uncapping on transfer