Short answer: For 2026, the Travis County ZIP codes showing the highest median over-assessment for property taxes are 78701 (Downtown Austin) at 11.8%, followed by 78747 (Onion Creek) at 10.3%, and 78645 (Lago Vista / NW lakeshore) at 8.1%. This data indicates a pattern where homes in these specific areas are more frequently assessed above their true market value compared to similar properties.
- 78701 leads with 11.8% median over-assessment.
- Over-assessment means assessed above comparable homes.
- Not every home in a top ZIP code is over-assessed.
- Protest deadlines are critical: May 15 or 30 days after notice.
- Use appraisal data to challenge your property value.
- Free tools can help homeowners check their potential gap.
Understanding Property Tax Over-Assessment in Travis County
Property taxes are a significant expense for Texas homeowners, and ensuring your appraisal district assesses your home fairly is key. An ‘over-assessment’ occurs when your property’s appraised value, set by the county appraisal district (like TCAD in Travis County), is higher than its actual market value or higher than the value of comparable homes in your area. Texas Tax Code 41.43(b)(3) allows homeowners to protest if their property is valued unequally compared to similar properties. This is often referred to as an ‘equal and uniform’ protest.
This report highlights areas in Travis County where a pattern of over-assessment is more prevalent, based on 2026 data. Keep in mind that these are median figures, indicating a general trend rather than a guarantee for every single home within a ZIP code.
Travis County's Top ZIP Codes for Property Tax Over-Assessment in 2026
Our data for 2026 reveals specific Travis County ZIP codes where homeowners are more likely to face over-assessments. Topping the list is 78701 (Downtown Austin), with a median over-assessment of 11.8% and a median overage of $111,650 for the 1,467 homes affected. This indicates a substantial ‘gap’ for many downtown properties.
Following closely is 78747 (Onion Creek), showing a median over-assessment of 10.3%. Here, 2,132 homes are over-assessed, with a median dollar overage of $33,422. The third highest is 78645 (Lago Vista / NW lakeshore), where the median over-assessment stands at 8.1%, affecting 2,045 homes with a median overage of $34,461.
Other significant areas include:
- 78758 (North Austin / Gracy Farms): 8.1% median over-assessment, $28,885 median overage for 1,828 homes.
- 78744 (Southeast Austin): 7.3% median over-assessment, $23,579 median overage for 2,810 homes.
- 78669 (Spicewood): 7.3% median over-assessment, $55,702 median overage for 1,064 homes.
- 78734 (Lakeway): 7.3% median over-assessment, $50,885 median overage for 2,520 homes.
What Do These Numbers Mean for Your Home?
It’s important to understand that a high ranking for a ZIP code signifies a statistical pattern, not a certainty that your individual home is over-assessed. ‘Median over-assessment’ refers to the midpoint of over-assessment percentages found within that ZIP code, meaning half of the over-assessed homes had a higher percentage and half had a lower.
The ‘Top-quartile (p75)’ figure gives you insight into the higher end of the over-assessment spectrum. For example, in 78701, while the median is 11.8%, 25% of the over-assessed homes faced an over-assessment of 19.4% or more. This illustrates the potential for significant discrepancies.
If your home is in one of these ZIP codes, or even if it’s not, checking your property’s specific assessment against comparable homes is a smart move. Many homeowners find that their property is appraised higher than similar homes in their neighborhood. You can use a free tool like the Tax Gaps TX home check to quickly see your estimated over-assessment gap for Travis, Dallas, or Fort Bend county by entering your address. This tool uses public appraisal data to identify properties assessed for less than yours, providing valuable evidence.
Why Do Over-Assessments Happen?
County appraisal districts use mass appraisal techniques to value millions of properties annually. While efficient, this method can sometimes overlook the unique characteristics or condition of individual homes, leading to inaccuracies. Rapid changes in the housing market can also contribute; if values decline, appraisal districts might be slow to adjust, or if specific micro-markets within a ZIP code shift, the broad strokes of mass appraisal may not capture it accurately.
Another common reason is simply a lack of up-to-date information on the appraisal district’s part regarding your property or recent sales of comparable homes. This is where homeowner vigilance and a well-prepared protest can make a significant difference.
Taking Action: How to Protest Your Property Value
If you suspect your property is over-assessed, the good news is that Texas law provides a clear process for protest. The standard deadline to protest your property value is May 15 or 30 days after your Notice of Appraised Value is mailed, whichever is later. It is crucial to verify the exact deadline with the Travis Central Appraisal District (TCAD) for your specific property.
Your protest can be based on several grounds, including unequal appraisal (your home is assessed higher than comparable properties), or if your appraised value exceeds market value. Gathering evidence of comparable sales or assessments is key. This could include sales of similar homes in your neighborhood, photos of your home’s condition compared to others, or even a professional appraisal.
After filing a protest, you’ll typically have an informal review with an appraiser, followed by a formal hearing with the Appraisal Review Board (ARB) if an agreement isn’t reached. If still unsatisfied, options like binding arbitration may be available. Remember, deadlines and exemption amounts can change yearly, so always confirm current figures with your county appraisal district or the Texas Comptroller’s office.
Beyond the Top Rankings: Other Travis County ZIPs with Notable Gaps
While 78701, 78747, and 78645 lead the list for median over-assessment, other Travis County ZIP codes also show significant patterns. For instance, 78617 (Del Valle) has a median over-assessment of 7.2% for 1,389 homes, with a median overage of $18,437. 78613 (Cedar Park), with 804 homes over-assessed, shows a 7.1% median over-assessment and a $43,053 median overage. Even 78705, with 1,039 over-assessed homes, presents a 6.7% median over-assessment and a $19,907 median overage.
These figures emphasize that property tax over-assessment is a widespread issue, affecting a broad range of neighborhoods and home values across Travis County. Regardless of your specific ZIP code, understanding these trends can empower you to investigate your own property’s assessment and ensure you’re not overpaying.
How we calculated this
These rankings come from Travis County’s own 2026-07 appraisal roll (492,218 parcels), analyzed with the same equal-and-uniform method the Texas Tax Code lets you use to protest (§41.43(b)(3)). For every residential home we find its comparable group — homes of the same class, neighborhood code, and age band — and take the median improvement value per square foot of that group as the fair rate. A home is counted as over-assessed when its improvement value sits more than 5% above what that fair rate implies for its size. Each ZIP code’s figure is the median gap among its over-assessed homes, so it is not skewed by a handful of outliers.
The numbers describe patterns, not any single property. Your home may be assessed fairly even in a high-ranking ZIP code, or over-assessed in a low-ranking one — the only way to know is to check your specific address.
Understanding Travis County Over-Assessment Data Points
| Over-Assessment Metric | What It Means for Homeowners | Example (78701 ZIP Code) |
|---|---|---|
| Median Over-assessment | The midpoint percentage of how much over-assessed homes are valued above comparables in a ZIP code. | 11.8% |
| Top-quartile (p75) | The percentage at which 25% of over-assessed homes are valued even higher than this figure. | 19.4% |
| Homes Over-assessed | The number of residential properties in the ZIP code identified as over-assessed. | 1,467 |
| Median $ Overage | The typical dollar amount that an over-assessed homeowner could potentially save if their property value were adjusted fairly. | $111,650 |
Check your home in minutes
Tax Gaps TX has a free home check at app.taxgapstx.com/check — enter your address and, in about a minute, see your estimated over-assessment gap for Travis (TCAD), Dallas (DCAD), or Fort Bend (FBCAD) county, based on public appraisal data and comparable homes assessed for less than yours. A specialist can then walk you through the evidence and whether it's worth protesting.
Frequently asked questions
What is 'median over-assessment'?
Median over-assessment is the middle value of all over-assessment percentages found in a specific ZIP code. It means half of the over-assessed homes in that area had a higher percentage and half had a lower percentage of over-assessment.
Does a high over-assessment percentage mean my home is definitely over-assessed?
Not necessarily. A high median over-assessment percentage in your ZIP code indicates a strong pattern of over-assessment for many homes in that area, but it doesn't guarantee your specific home is over-assessed. You need to check your individual property's appraisal against comparable homes.
What is the deadline to protest my property taxes in Travis County for 2026?
The general deadline to protest property taxes in Texas is May 15 or 30 days after your Notice of Appraised Value is mailed, whichever date is later. Always confirm the exact deadline for your specific property with the Travis Central Appraisal District (TCAD).
What is an 'equal and uniform' protest?
An 'equal and uniform' protest is a challenge to your property's appraised value based on the argument that it is valued unequally compared to similar properties in your neighborhood. Texas Tax Code 41.43(b)(3) allows homeowners to make this type of protest.
Where can I find my official property tax information and deadlines?
For official property tax information, including your appraised value, exemptions, and protest deadlines, you should always refer to the website of your specific county appraisal district (e.g., Travis Central Appraisal District for Travis County) or the Texas Comptroller's office.
Tax Gaps TX provides general information, not legal, tax, or financial advice. Deadlines and exemption amounts change; confirm current figures with your county appraisal district or the Texas Comptroller.