It never visits your house. It models your neighbourhood, from sales data Texas law does not entitle it to see. Here is where your number really comes from.
Check your home FREE →HCAD never visits your house. It builds a computer model of your whole neighbourhood, from sales data Texas law does not entitle it to see, and your value falls out of that model. Once you understand that, the way to argue with it stops being a mystery. This page explains where the number comes from, what the two numbers on your HCAD page actually mean, and why your neighbour can pay less than you on an identical house without anyone having done anything wrong.
Open your property on HCAD's website and you will find two figures. People use them interchangeably. They are not interchangeable, and mixing them up is the most common mistake a homeowner makes.
| What it says | What it means |
|---|---|
| Market value | What HCAD's model thinks the house would sell for on 1 January. This is an opinion. Texas law defines it (Tax Code §1.04(7)) as the price a property would sell for after being openly on the market for a reasonable time, with both sides informed and neither one able to take advantage of the other's situation. |
| Appraised value | That figure after the 10% homestead cap is applied (§1.04(8) and §23.23). This is the number your tax is actually calculated from. |
For most homes these are the same figure printed twice. For a home that has carried a homestead exemption for years they come apart, sometimes dramatically, because the cap limits how fast the taxable figure may climb no matter what the market did.
Here is one real, entirely ordinary Harris County home, sitting right in the middle of that group. HCAD's model says it would sell for $142,436. Its taxes are calculated on $116,588. Nothing about the house changed to produce that $25,848 difference — the gap is entirely the cap.
Once your home has a homestead exemption, the law limits how fast HCAD may raise your appraised value: 10% a year, maximum, however fast the market moved (Tax Code §23.23).
Market value can jump 25% in a year. Appraised value — the one your bill is calculated from — can only move 10%. So every year the market runs faster than the cap allows, the two numbers drift further apart. That is the whole reason a long-time owner's appraised value sits so far below their market value. Nothing has been fiddled. The law has been holding one number back for years.
This is the part that catches people out, and it is worth two minutes.
Take the home above, which has been capped for years: taxed on $116,588 while the model says it is worth $142,436. Now suppose you buy the identical house next door. No cap has built up for you yet, so you are taxed on the full $142,436.
| Same house, same street | Market | Appraised |
|---|---|---|
| Neighbour, owned for years | $142,436 | $116,588 |
| You, bought last year | $142,436 | $142,436 |
Look at the appraised column and you appear to be $25,848 over-valued against an identical house. You are not. Your value is correct. Theirs is low because the law has been protecting them for years and has not started protecting you yet.
Texas is a non-disclosure state. When a house sells here, nobody is required to tell anyone what it sold for. It does not go in the public record.
So the appraisal district, which carries 1,623,565 real-property accounts worth about $771.5 billion on its own roll, cannot simply look up what houses sold for. Instead it does mass appraisal: it sorts property by size, age, construction type, use and location, then values whole classes at once from whatever sales information it can assemble. Harris County single-family homes alone are split into 5,887 neighbourhood codes — groups of homes the district has decided behave as one market.
The law expects exactly this. Tax Code §23.01(b) requires generally accepted appraisal methods, and says that where a district uses mass appraisal, the standards must comply with the Uniform Standards of Professional Appraisal Practice. But the same subsection also says each property "shall be appraised based upon the individual characteristics that affect the property's market value", and that all available evidence specific to your property shall be taken into account. That sentence is your answer to "it is a mass appraisal, nothing personal" — the model is lawful, and so is your right to put your own house's facts in front of it.
There are two ways to protest, and the difference matters more than most people realise.
Tax Code §41.43(b) puts the burden on the district: an unequal-appraisal protest is decided in the owner's favour unless HCAD disproves it. That is why it is the workhorse of a do-it-yourself protest, and it is the argument our free check runs for you. You can file on both grounds at once, and the protest form we prepare does exactly that.
And you are entitled to make the argument yourself: §23.01(g) says an owner representing themselves may offer an opinion of value and present argument and evidence. You do not need an agent to be heard.
Next: how we choose your comparable homes — every rule we apply, in full. No black box.
Market value is what HCAD's model thinks your home would sell for on 1 January. Appraised value is that figure after the 10% homestead cap is applied, and it is the number your tax bill is calculated from. For most homes they are identical. For 163,495 Harris County homes — about one in seven — they are not, because the cap is holding the appraised figure down.
Once a home has a homestead exemption, Texas Tax Code §23.23 only lets its appraised value rise 10% a year however fast the market moves. A neighbour who has owned for years has had that brake applied the whole time. If you bought recently, no cap has built up for you yet, so you are taxed on the full market figure. Same house, different number — and that is the law working, not a mistake.
No. HCAD values roughly 1,623,565 real-property accounts using mass appraisal — sorting property by size, age, construction type and location and valuing whole groups at once. Texas Tax Code §23.01(b) permits this, but requires the standards to comply with USPAP and still requires each property to be appraised on the individual characteristics that affect its market value.
It largely does not. Sale prices are not required to be publicly recorded in Texas, so the district assembles what it can from voluntary disclosures, industry sources and surveys — and from closing statements that homeowners hand over during protests. HCAD's own material acknowledges it does not obtain sale prices on all transactions.
No, and they are constantly confused. The exemption removes $140,000 from the value your school taxes are calculated on (§11.13(b)). The cap limits how fast your appraised value may rise, to 10% a year (§23.23). They are separate protections and most homeowners have both.
Last updated: August 29, 2026 · Harris County, Texas. Figures on this page are generated from HCAD's own public appraisal roll, not typed in by hand.