Property tax assessment appeal calculator

How to appeal property taxes with comparable sales

To appeal, you show that your home would have sold for less than the value on your notice, usually with recent sales of similar homes nearby. The steps are the same almost everywhere:

1. Read your notice. Note the value, the valuation date and the appeal deadline printed on it. Check the property record for errors in living area, bedrooms, baths or condition: a wrong square footage is the easiest fix.
2. Pick 3 to 5 comparable sales. Same neighborhood, similar size, age and style, sold close to the valuation date. Closing statements, deeds or the assessor's own sales list are better evidence than an online estimate.
3. Adjust for differences. If a sale had a pool you lack, subtract what the pool adds; if your home needs a roof, the sale price of a home with a new roof should come down. Enter those amounts in the adjustment field.
4. File on time with the right body, using the county's form or portal in the table below, and bring the printed summary, the sale records and photos to the hearing.

Texas, for example, asks owners to protest to the appraisal review board and accepts sales of comparable properties, photos and repair estimates as evidence.^[6] To see what a lower value does to the whole bill, use the property tax calculator; for Texas homes, the Texas property tax calculator also shows the 10% homestead cap.

Property tax appeal: how the calculator estimates fair value from comparable sales

The calculator uses a price-per-square-foot comparison, the simplest sales method a board can check line by line:

Indicated value = (sale price + adjustment) ÷ sale's living area × your living area

It computes one indicated value per sale and takes the median, the middle value, so one odd sale cannot swing the answer; the mean and the range are shown as a check. The value to ask for is the lower of that median and your notice value. The tax at both values runs through the same engine as the county calculators, with the county's assessment ratio, exemptions and adopted rates by taxing unit, so the savings figure is the difference on your actual bill lines, not a flat national rate. Sales more than two years old are flagged so you can swap in sales closer to the valuation date.

Property tax appeal deadlines by county

Appeal windows are short and they differ by state: a Texas property tax protest is due May 15 or 30 days after the notice, California's regular window ends September 15 or November 30, and Cook County opens township by township. A date is listed only where the county or state published it; otherwise check the notice.

Payment deadlines are a separate calendar: see property tax due dates. An appeal does not pause your bill; pay on time and any refund follows the decision.

Three real homes run through the calculator

These examples use real values from county assessor records and real recorded sales near each home, entered exactly as an owner would. Addresses and parcel numbers are left out.

Los Angeles County: 2,090 sq ft 1973 house, Chatsworth (City of Los Angeles)

The owner bought this four-bedroom house in May 2024 for $1.2 million, and Prop 13's 2% yearly trend put the 2026-27 roll value at $1,248,479. Four sales nearby, three in the same 1973 tract, are entered at their recorded prices with no adjustments; in California a value below the trended Prop 13 base is a decline-in-value (Prop 8) appeal.^[31][13] The 4 sales put the median value at $1,229,208, 1.5% below the $1,248,479 on the roll; at Los Angeles County's adopted rates the estimated tax falls from $14,721.77 to $14,493.25, a possible saving of $228.52 a year.

King County: 1,090 sq ft 1954 house, north Seattle

The Assessor valued this three-bedroom rambler at $651,000 as of January 1, 2026 (for 2027 taxes). Four 2025 sales of similar small houses in the same Assessor neighborhood come from the Assessor's own sales file; the tax uses Seattle's latest adopted (2026) levy rate because 2027 rates are not set yet.^[32][33] The 4 sales put the median value at $630,555, 3.1% below the $651,000 on the roll; at King County's adopted rates the estimated tax falls from $6,450.40 to $6,247.82, a possible saving of $202.58 a year.

Miami-Dade County: 1,762 sq ft 1935 house, Shenandoah (City of Miami)

The Property Appraiser's 2026 just value for this homesteaded house is $649,615. Three qualified 2024 sales on the same blocks, from the Property Appraiser's own records, all sold for more per square foot.^[34][29] The 3 sales put the median value at $872,238, above the $649,615 on the roll, so they would not support an appeal: the calculator shows $0.

Property tax protest mistakes that sink an appeal

• Arguing about the tax, not the value. The board rules on your home's value (and errors or exemptions); tax rates are set by the county, city, school and other taxing units.
• Sales from the wrong date or area. A sale two years before the valuation date or across a school boundary is weak evidence.
• Listing prices or online estimates. Use closed sales; asking prices are not evidence of value.
• Missing the window. In Cook County, once a township closes the next chance is the following year.^[2] Seniors and veterans should also check property tax exemptions for seniors, which can save more than an appeal.

A property tax appeal letter is optional in most counties: the official form or portal is what counts. The printed summary from this calculator works as the attachment or the outline of what you say at the hearing.