Key Takeaways
- BCAD uses approximately 101 field appraisers to value 774,065 parcels — a ratio of roughly 7,664 properties per appraiser — forcing heavy reliance on statistical models that miss individual property conditions.
- The Computer Assisted Mass Appraisal (CAMA) system groups properties into market areas and values them as statistical cohorts, not as individual homes with unique characteristics.
- Appraisers never enter your home — exterior-only inspections on a three-year cycle mean foundation issues, outdated kitchens, water damage, and deferred maintenance are invisible to the model.
- Texas is a non-disclosure state — sellers are not required to report sale prices, forcing BCAD to build its comparable sales database from incomplete data.
- The Texas Comptroller's ratio studies show Bexar County meets aggregate accuracy standards, but aggregate accuracy masks individual errors — roughly 40% of homes are assessed above their actual market value.
- Federal Reserve and University of Chicago research confirms mass appraisal is systematically regressive — lower-value homes are assessed at higher percentages of their true market value than expensive homes.
- Every systematic limitation of the CAMA model is a specific, documentable argument you can raise in a property tax protest.
The Bexar Central Appraisal District (renamed January 1, 2026) employs 194 total staff under Chief Appraiser Rogelio Sandoval, with a $25.9 million annual budget serving 81 taxing units.
Your property tax bill starts with a single number: the assessed value BCAD assigns to your home. If that number is wrong, every taxing entity — the city, the county, University Health, your school district — multiplies its rate against an inflated base. Understanding how BCAD produces that number, and where the process systematically breaks down, is the foundation of an effective protest.
Decision guide
Not all CAMA errors look the same. The type of error determines what evidence you need to counter it.
Most overassessed homes have more than one error type. Start with data errors — incorrect square footage alone can account for $30,000–$50,000 in excess valuation and is the easiest to prove.
How BCAD values your property
BCAD uses Computer Assisted Mass Appraisal (CAMA) software to generate values for hundreds of thousands of properties simultaneously. The primary residential method is the cost approach — calculating the replacement cost of the structure minus depreciation, adjusted for local market conditions. Properties are grouped into market areas and valued as statistical cohorts.
The process works in three layers:
- Data collection. Physical characteristics (square footage, year built, construction type, lot size) are gathered through exterior inspections, aerial photography, building permits, and property owner renditions.
- Model calibration. BCAD calibrates its cost and market models using whatever sale price data it can collect — voluntary disclosures, surveys, third-party data, and MLS feeds. The models assign adjustment factors for location, condition grade, and property features.
- Mass valuation. The calibrated model produces values for every property in each market area simultaneously, targeting January 1 market conditions.
BCAD's Reappraisal Plan describes a three-year physical inspection cycle using drive-by exterior review, aerial photography, and GIS sketch overlay. Interior inspections are not part of the standard residential appraisal process.
Texas Property Tax Code §25.18 requires appraisal districts to inspect each property at least once every three years. In practice, "inspection" means an exterior drive-by — appraisers never enter your home unless you invite them for a reappraisal review.
The staffing reality
The math is straightforward. BCAD appraises 774,065 parcels with approximately 101 field appraisers. That is roughly 7,664 properties per appraiser — assuming every appraiser carries an equal load, which they do not since some cover commercial and special-use properties.
Under the three-year inspection requirement, each appraiser must physically review approximately 2,555 properties per year — roughly 10 per working day. At that pace, each "inspection" averages about 45 minutes including drive time, photograph capture, sketch verification, and data entry. There is no time for nuance.
This is not a criticism of BCAD's staff — the workload is a structural constraint imposed by the scale of Bexar County's property base and the district's budget. But it means the system is designed for statistical adequacy at the aggregate level, not accuracy at the individual property level.
Known limitations of mass appraisal
Interior condition blindness
BCAD appraisers never enter your home. The CAMA model assigns a condition grade based on exterior observation, age, and construction class — but it cannot see foundation cracks in the slab, galvanized plumbing that needs replacement, a kitchen that has not been updated since 1985, or water damage behind walls.
A home that looks presentable from the street but needs $40,000 in interior work will be valued the same as its fully renovated neighbor. The model has no mechanism to distinguish between them without owner-provided information.
If your home has significant interior condition issues — foundation problems, outdated systems, deferred maintenance, water damage — the CAMA model almost certainly overstates its value. Document these issues with dated photographs and contractor estimates. This is some of the strongest protest evidence you can present.
Non-disclosure state
Texas is one of approximately a dozen states where sellers are not required to report sale prices to the appraisal district. This is established under Texas Property Tax Code §22.01 — the rendition form asks for property description and usage, not transaction price.
BCAD compensates by collecting sale data through voluntary disclosure questionnaires, MLS data feeds, title company cooperation, and third-party vendors. But coverage is incomplete. Industry estimates suggest Texas appraisal districts capture 50–70% of residential transactions, meaning 30–50% of sales are invisible to the model.
The result: BCAD's comparable sales database has systematic gaps. When the model lacks sufficient sale data in a neighborhood, it falls back on broader market area adjustments — which may not reflect the micro-market dynamics of your specific block or subdivision.
Texas does not require disclosure of real property sale prices. The IAAO Standard on Ratio Studies notes that non-disclosure states face inherent data quality challenges in calibrating mass appraisal models.
Neighborhood boundary errors
BCAD divides the county into market areas — geographic zones assumed to have similar property value dynamics. Properties within each market area receive the same location adjustment factors.
The problem is that real estate markets do not respect administrative boundaries. A street that borders two market areas may have homes on one side valued using different adjustment factors than homes on the other side. A subdivision adjacent to a new commercial development may see value impacts that the broader market area model does not capture. Micro-markets within a single market area — a flood-prone pocket, a cul-de-sac backing to a highway, a section with older infrastructure — are averaged away.
Time lag
All Texas property is appraised as of January 1 of the tax year. BCAD must set values based on market conditions as of that date using data available at the time the appraisal roll is produced (typically March–April).
In a declining or volatile market, this creates a structural lag. If prices fell between January and April, BCAD's January 1 snapshot may already be stale by the time you receive your Notice of Appraised Value. Conversely, if the market softened in the second half of the prior year, the trailing data BCAD used to calibrate its model may not fully capture the decline.
This lag effect is particularly pronounced in San Antonio's current market. With homes spending 86–97 days on market and over half of listings requiring price cuts, the gap between BCAD's January 1 snapshot and actual market conditions is wider than usual.
The ratio study problem
The Texas Comptroller conducts biennial ratio studies to evaluate whether appraisal districts are valuing property accurately. These studies compare appraised values to actual sale prices and calculate statistical measures of accuracy.
The International Association of Assessing Officers (IAAO) establishes the statistical benchmarks used by the Texas Comptroller to evaluate appraisal district performance.
Bexar County's aggregate ratio study metrics generally fall within IAAO acceptable ranges. But here is the critical distinction: aggregate accuracy does not mean individual accuracy. A county can have a perfect median ratio of 1.00 while half of homes are overassessed by 20% and the other half are underassessed by 20%. The median looks fine. Individual homeowners are paying hundreds or thousands of dollars in excess taxes.
The COD metric captures this dispersion, but even a "passing" COD of 10–15 means significant individual variation exists. A COD of 12 on a $300,000 home means individual assessments vary by roughly $36,000 above and below the median — a range that translates to $828 per year in tax variation at a 2.3% combined rate.
The regressivity problem
Academic research has consistently documented that mass appraisal systems are regressive — they assess lower-value homes at higher percentages of their true market value than expensive homes.
The Federal Reserve Bank of Philadelphia found that among single-family homes subject to the same nominal tax rate, owners of inexpensive homes pay effective tax rates up to 50% higher than owners of expensive homes. The study attributed approximately 60% of this regressivity to flawed valuation methods and 40% to infrequent reappraisal.
Among single-family homes subject to the same tax rate, owners of inexpensive houses pay almost 50% higher effective tax rates than owners of expensive houses, due primarily to assessors' flawed valuation methods.
The University of Chicago's Property Tax Fairness Project, led by Professor Christopher Berry, analyzed assessment data from thousands of counties nationwide and found the same pattern. Lower-value properties are systematically over-assessed relative to their sale prices, while higher-value properties are under-assessed. Berry's research was published in the Washington Post, cited in testimony before Congress, and contributed to assessment reform efforts in multiple states.
In Bexar County, the San Antonio Report documented that "homes of the lowest value in Bexar County are being overtaxed compared to homes that are worth more" — consistent with the national pattern.
Regressivity means the overassessment problem hits hardest in lower-value neighborhoods — the South Side, West Side, and East Side of San Antonio — where homeowners can least afford excess tax burden. If your home is valued under $200,000, the statistical likelihood of overassessment is higher than average.
What this means for your protest
Every systematic limitation of the CAMA model is a specific, documentable argument you can raise in a property tax protest:
- Data errors → Pull your BCAD property detail page and verify every field against reality. Wrong square footage, bedroom count, or lot size is an objective factual error that BCAD must correct.
- Interior condition → Photograph every issue that reduces value. Get contractor estimates. Present evidence the model cannot see.
- Market lag → Gather recent comparable sales that closed after BCAD's data cutoff. Show the gap between the January 1 snapshot and actual market conditions.
- Non-disclosure gaps → Present your own comparable sales analysis using verified MLS data. If BCAD's comps are weak or outdated, your evidence fills the gap.
- Neighborhood misclassification → Show that your specific micro-market behaves differently from the broader market area BCAD assigned.
- Unequal appraisal → Show that comparable properties in your area are assessed at lower values per square foot. This is the unequal appraisal argument under Tax Code §42.26 — and it does not require proving market value at all.
The system is not designed to get your individual value right. It is designed to be statistically adequate across hundreds of thousands of properties. When it gets yours wrong, the only correction mechanism is a protest.
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Methodology
All data in this analysis is sourced from primary government, institutional, and academic research sources. Assessment data reflects BCAD's 2025 appraisal year.
Staffing and parcel data (774,065 parcels, 194 total employees, 101 field appraisers, $25.9M budget) are from BCAD's 2025 Annual Report.
Mass appraisal methodology data is from BCAD's 2025–2026 Reappraisal Plan, supplemented by IAAO Standards on Mass Appraisal of Real Property and the Texas Comptroller's Property Tax Assistance Division.
Ratio study standards (COD, PRD, median ratio benchmarks) are from the IAAO Standard on Ratio Studies (2013 edition) and the Texas Comptroller's Property Value Study methodology.
Regressivity research is from three primary sources: University of Chicago Property Tax Fairness Project (Christopher Berry), Federal Reserve Bank of Philadelphia Working Paper 22-02 (Natee Amornsiripanitch, January 2022), and local reporting from the San Antonio Report.
Non-disclosure state context is from Texas Property Tax Code §22.01 and IAAO guidance on ratio study methodology in non-disclosure jurisdictions.
Sources:
- BCAD Annual Report 2025
- Texas Comptroller — Property Tax Assistance
- IAAO Standards
- University of Chicago Property Tax Fairness Project
- Federal Reserve Bank of Philadelphia — Working Paper 22-02
- San Antonio Report — Property Tax Regressivity
Common questions
What is CAMA and how does BCAD use it?
CAMA stands for Computer Assisted Mass Appraisal. It is the software system BCAD uses to generate property values for all 774,065 parcels in Bexar County simultaneously. The system groups properties into market areas, applies cost and market models calibrated from available sale data, and produces assessed values as of January 1 each year. The primary residential method is the cost approach — replacement cost minus depreciation, adjusted for local conditions.
Why can't BCAD get my individual home value right?
BCAD's mass appraisal system is designed for statistical accuracy across hundreds of thousands of properties — not precision for individual homes. With approximately 101 field appraisers covering 774,065 parcels, exterior-only inspections, and incomplete sale data due to Texas's non-disclosure law, the system inevitably produces individual errors even when aggregate metrics look acceptable. Roughly 40% of Bexar County homes are assessed above their actual market value.
How often does BCAD physically inspect my property?
Texas law requires appraisal districts to inspect each property at least once every three years. In practice, BCAD's "inspection" is an exterior drive-by — appraisers view the property from the street, compare aerial photography, and verify building sketches. They never enter your home unless you specifically request an interior review as part of a reappraisal.
What is a ratio study and why does it matter?
A ratio study compares assessed values to actual sale prices to measure appraisal accuracy. The Texas Comptroller conducts these biennially. Key metrics include the median ratio (should be 0.90–1.10), coefficient of dispersion or COD (should be 5–15 for residential), and price-related differential or PRD (should be 0.98–1.03). Bexar County generally passes aggregate standards, but passing at the county level does not mean your individual assessment is accurate — significant variation exists within acceptable aggregate ranges.
Are lower-value homes assessed higher relative to their sale price?
Yes. Research from the Federal Reserve Bank of Philadelphia, the University of Chicago Property Tax Fairness Project, and local San Antonio reporting all confirm that mass appraisal systems are systematically regressive. Lower-value homes are assessed at higher percentages of their true market value than expensive homes, meaning owners of less expensive properties pay disproportionately higher effective tax rates. The Fed study found the gap can reach 50%.
Can I protest a data error in BCAD's records?
Absolutely — and you should. Data errors are among the strongest protest grounds because they are objective and verifiable. Common errors include incorrect square footage, wrong bedroom or bathroom count, inaccurate lot size, incorrect year built, and phantom improvements (additions or features that do not exist). Pull your property detail page from BCAD's website and verify every field against your home's actual characteristics. If you find errors, bring documentation — builder plans, surveys, or photographs with measurements.