How the check works.

01

What the check compares, and why

You can protest your appraisal on two grounds. One is that the value is higher than the home would sell for. The other is that it’s unequal: your home is valued higher than comparable homes. Texas doesn’t make sale prices public, so the first is hard to prove from public records. The second can be built entirely from them, and that’s the one our check runs.

A protest on unequal appraisal “shall be determined in favor of the protesting party unless the appraisal district establishes that” one of the tests in the section is met. The test built from comparable homes: the appraised value “is equal to or less than the median appraised value of a reasonable number of comparable properties appropriately adjusted.”

Tax Code 41.43(b)(3)

Look at who carries the burden. You don’t have to prove your home is overvalued. The district has to show it isn’t valued above the median of comparable homes, adjusted. Our check runs that median test, with the district’s own records, before you file.

Two more sections shape the method. Tax Code 42.26(d), the rule for appeals in district court, says that for a homestead under the 10% cap the comparison uses market value, for your home and for the comparables, not the capped value. We apply that rule at every stage and use market value for every home. Tax Code 23.013(d) lists what makes properties comparable in a sales comparison: location, the size of the lot and the building, age, condition, access, amenities, and views, among others. It’s written for market-value appraisals, not for equal appraisal, so we treat it as guidance on which differences to match or adjust for.

The law doesn’t define “reasonable number” or “appropriately adjusted.” Review boards and courts decide those on the evidence in each case. So the method has to be open, and the rest of this page lays it out.

02

How comparables are chosen

We start from every single-family home and townhome in your appraisal district’s file for the year and keep the ones that match yours on the points below. If that first pass finds fewer than eight, we widen the search once.

What we leave out

• Your own home.
• Properties with more than one living building, which don’t compare cleanly to one house.
• In Harris, homes with new construction this year, buildings HCAD lists as unfinished, and records missing the factors the adjustment needs.
• Any comparable whose adjusted value lands more than 25% away from its own market value. A home that needs that much adjusting isn’t comparable, so it drops out and the next one comes in.

Ranking and the count

The survivors are ranked by how close they are to your home: the difference in living area as a share of yours, plus half the difference in effective age in decades, plus a step for each condition grade apart (Harris), plus a penalty for being outside your neighborhood. We keep the closest 15.

If fewer than five homes are left, we don’t show a number. We say the data can’t support a fair comparison for that home. We never drop a comparable because it raises the median: the review board sees the same records we do.

03

How the adjustments work

Each comparable is adjusted to your home, so the question becomes: what would this neighbor’s value be if it had your lot, your size, and your age? The median of those adjusted values is the number the law asks about.

Harris County: HCAD’s own factors

HCAD publishes the factors it uses to value each building. We adjust with those, so every step uses the district’s own schedule, not a rate we picked.

adjusted = your land value + your extra features
         + their building value
           × size     (your area × your size index) ÷ (their area × their size index)
           × condition (your percent good ÷ their percent good)
           × grade     (your grade factor ÷ their grade factor)
           × location  (your neighborhood factor ÷ theirs)

• Land and extra features. Your land value and your pool, garage, and outbuilding values replace theirs. That removes lot size, corner lots, and floodway land from the comparison.
• Size. HCAD’s size index lowers the rate per square foot as homes get bigger, so a smaller neighbor isn’t scaled up at its higher per-foot rate.
• Age and condition. HCAD’s percent good already combines effective age and condition, so one ratio covers both.
• Grade and location. The ratio of grade factors, and of neighborhood factors. Inside one neighborhood the location ratio is 1; it matters only when the search widened.

The other 29 counties: rates fit to each neighborhood

Most districts don’t publish their valuation factors, so we measure them from the neighborhood’s own values. Two rates do the work: how building value grows with living area, and how much a year of effective age is worth.

adjusted = your land value
         + their improvement value
           × (your living area ÷ their living area) ^ b
           × e ^ ( r × (your effective year − their effective year) )

• b, the size rate. For each neighborhood with 30 or more homes, we fit a straight line through the log of improvement value against the log of living area. The slope is b. A b of 0.8 means a home 10% larger carries about 8% more building value.
• r, the age rate. With size taken out, we fit what’s left against effective year built. The slope is r, the share of value a year of age is worth.
• Bounds. b is held between 0.4 and 1.1 when it’s fit, and capped at 0.95 when it’s used, because a home twice the size is rarely worth twice as much. r is held between 0 and 3% a year. A neighborhood with fewer than 30 homes uses its county’s rates.

Across the 18,067 neighborhoods with their own rates, the median b is 0.78 and the median r is 0.80% a year. In 4,944 of them the fit came out above 0.95, so the check uses 0.95. The rates are refit every time a county’s file is loaded.

Outside Harris, the check matches homes on class instead of adjusting for quality and condition, because most districts don’t publish a condition rating. These files don’t separate pools and outbuildings from the building value, so a comparable’s pool stays in its value and is scaled with it.

04

A worked example

One real check from Harris County’s 2026 roll, run by the same code as the site. We’ve left out house numbers and account numbers; the street names and every value are as HCAD publishes them.

Subject

A house on DUNKLEY DR, 77076 (GLEN OAKS)

Living area

1,304 sq ft

Effective year built

1956

Grade, condition

C-, average

Land, extra features

$40,140, $503

Market value

$163,581

Appraised (capped) value

$160,314

Scroll the table sideways for each adjustment.

Adjustment columns are the change to the comparable’s value from each step, in order. Land and features swap in the subject’s values. The highlighted row is the median.

The market value sits $4,317 (2.6%) above the median of 15 adjusted comparables, which clears the threshold below. The value to request is the median rounded down to the nearest $1,000. This home is under the cap, so its taxable value is $160,314. A win at $159,000 would lower the taxable value by $1,314.

05

Market value and appraised value

Your notice shows two numbers. Market value is the district’s estimate of what the home would sell for. Appraised value is what you’re taxed on, before exemptions. For most homes they’re the same. For a homestead under the 10% cap (Tax Code 23.23), the appraised value is lower: it can rise only 10% a year, however fast the market value climbs.

Under Tax Code 42.26(d), an equal-appraisal case for a capped homestead compares market values, yours against the comparables’. So the check finds the gap in market value. But a market value cut lowers your bill this year only if the new value falls below your capped appraised value. That’s why the result shows two numbers: the gap in market value, and what a win would take off your taxable value, which can be $0 even when the gap is real. A lower market value still matters for a capped home, because it shrinks the gap the cap will keep closing in later years.

06

When a gap is real

Adjustments are estimates, and the district rounds. A home that sits a few hundred dollars above the median isn’t meaningfully overvalued. We call a gap real only when your market value is above the adjusted median by at least $2,000 and by at least 1% of your market value, whichever is larger. Below that, the result says your value is in line with comparable homes, and we don’t suggest a value to request.

07

The tax calculator's assumptions

The calculator on the home page is separate from the comparables check. It turns a value into a yearly tax estimate.

• Rates. The Comptroller’s published rates for every county, school district, city, and special district, tax year 2025, retrieved October 7, 2026.
• School district. It starts on the district covering the most property value in your county. If yours is different, change it on the notice.
• State exemptions. A homestead takes $140,000 off the school district’s taxable value (Tax Code 11.13(b)), and $60,000 more if you’re 65 or older or disabled (11.13(c)).
• Left out. Local optional exemptions: many counties, cities, and some school districts give a percentage homestead exemption or a local over-65 amount, so your bill may be lower than the estimate. The $3,000 county road and flood control exemption is also left out.
• Over-65 ceiling. If you’re 65 or older, your school tax may be frozen at the amount from your first qualifying year (Tax Code 11.26). The calculator doesn’t model the ceiling, so it can overstate your school tax.
• The value you enter. Use the appraised value from your notice. That’s the capped value for a homestead under the cap.

Your bill can differ from the estimate. The bill from your county tax office is the one you owe.

08

Data sources by county

The check is live in 30 counties, covering 4,967,317 single-family homes and townhomes. Each comes from the appraisal district’s own published file for the tax year. Harris uses HCAD’s valuation factors; the other counties use rates fit to each neighborhood.

File date is the date on the district’s export, or the day we downloaded it when the file has none. Harris: HCAD public data, 2026 certified roll. Counties are added as their files are loaded; this table was built October 8, 2026.

09

Privacy

Appraisal records are public, and they include owner names. Ours don’t: we drop owner names and mailing addresses when we load each file, so they never reach our database. We keep the property address, values, and building details the check needs.

When you search for your home, the address goes to our server in the body of the request, not in the URL, and we don’t store it. The tax calculator runs in your browser. More in our privacy policy.

10

What the check can't see

The check knows what the district’s file knows. It can’t see a foundation problem, a kitchen from 1978, a busy road behind the fence, or flood damage the district hasn’t recorded. Those are arguments for your protest too, with photos and repair bids, and they’re yours to bring. It also doesn’t make a market-value case from sales, because Texas doesn’t publish sale prices.

A result is an estimate from public records, not a promised outcome. The review board weighs the evidence from both sides, and the district may bring comparables of its own.