Williamson County Property Tax Rate: 2025 Rates by Taxing Entity
In July 2025, catastrophic flash floods struck Williamson County, triggering disaster declarations from the county, state, and federal government -- and allowing the county to use a higher 8% revenue cap instead of the standard 3.5%. Even with that increase, the typical Round Rock homeowner faces a combined rate of approximately 1.68% of taxable value, or $1.68 per $100, spread across Round Rock ISD, the City of Round Rock, and Williamson County.
A Williamson County homeowner with a home valued at $420,000 -- near the county median -- pays approximately $7,051 per year in total property taxes before exemptions.
Williamson County Property Tax Rates by Taxing Entity (Tax Year 2025)
Your Williamson County property tax bill is the sum of taxes levied by every taxing entity that covers your property. Here are the current adopted rates for the major entities serving a typical City of Round Rock homeowner:
| Taxing Entity | Rate per $100 | Est. Tax on $420,000 Home | Share of Bill |
|---|---|---|---|
| Round Rock ISD | $0.8931 | $3,751 | 53% |
| Williamson County | $0.413776 | $1,738 | 25% |
| City of Round Rock | $0.372000 | $1,562 | 22% |
| Total (Typical) | ~$1.68 | ~$7,051 | 100% |
Important: Your exact rate depends on where you live in Williamson County. Properties in Municipal Utility Districts (MUDs) pay additional taxes that can add $0.25 to $1.40 per $100, with newer developments at the higher end. Emergency Services Districts (ESDs) add approximately $0.08 to $0.10 per $100 for most homeowners outside city limits.
Note on health district: The Williamson County and Cities Health District (WCCHD) does not levy its own property tax. It is funded through cooperative agreements among member governments, keeping the total number of taxing entities lower than in counties with standalone health or hospital districts.
Round Rock ISD: The Largest Share
Round Rock ISD accounts for roughly 53% of a typical Round Rock homeowner's property tax bill. The tax year 2025 rate of $0.8931 per $100 is the lowest among major Williamson County school districts. The rate breaks down as:
- Maintenance & Operations (M&O): $0.7101 per $100 (includes the state-mandated maximum compressed rate of $0.6301 plus 8 voter-approved enrichment pennies)
- Interest & Sinking (Debt Service): $0.1830 per $100
Round Rock ISD benefits from being a property-wealthy district with relatively low debt service, which keeps its overall rate well below most neighboring ISDs.
Other Major School Districts in Williamson County
Williamson County includes several school districts with varying rates:
| School District | 2025 Rate per $100 | Notes |
|---|---|---|
| Georgetown ISD | $1.0506 | M&O slightly decreased; I&S $0.3575 |
| Leander ISD | $1.0869 | Flat from prior year; rate lowered for 7 consecutive years before holding |
| Pflugerville ISD | $1.1069 | Unchanged from prior year |
| Hutto ISD | $1.2052 | I&S rate of $0.45 reflects substantial bond obligations |
| Liberty Hill ISD | $1.2389 | VATRE narrowly approved Nov 2025 (52%); 7-cent M&O increase |
Homeowners in these districts pay a significantly higher school tax rate than those in Round Rock ISD. A homeowner in Pflugerville ISD territory, for example, pays roughly $900 more per year in school taxes alone on the same home value.
How Williamson County Compares to Other Texas Counties
Williamson County's total property tax rate is among the lowest of major Texas metros:
| County / City | Approximate Total Rate | Median Home Value |
|---|---|---|
| Williamson County (Round Rock) | ~1.68% | $420,000 |
| Collin County (Plano) | ~1.71% | $500,000 |
| Travis County (Austin) | ~2.07% | $515,000 |
| Harris County (Houston) | ~2.03% | $320,000 |
| Dallas County (Dallas) | ~2.22% | $350,000 |
Williamson County's low rate relative to Travis County is notable because both counties are part of the Austin metro area. A homeowner moving from Austin to Round Rock can see a meaningful reduction in their effective tax rate. However, within Williamson County, effective rates vary dramatically by location -- from as low as 1.19% in Florence to 2.06% in Pflugerville.
How Williamson County Property Tax Rates Have Changed
Williamson County's tax rate has fluctuated in recent years, influenced by rapid population growth, infrastructure needs, and a catastrophic natural disaster:
| Year | Key Changes |
|---|---|
| 2022 | County rate dropped sharply to ~$0.3557 as property values surged |
| 2023 | Rate continued declining to ~$0.3331; state homestead exemption increased to $100,000; voters approved $825M road bonds and $59M park bonds |
| 2024 | County rate rose to ~$0.3999 as infrastructure spending increased |
| 2025 | Catastrophic July floods triggered disaster declaration; county rate increased to $0.4138 using disaster-year 8% revenue cap; Liberty Hill ISD VATRE approved; homestead exemption rises to $140,000 |
Williamson County is one of the 10 fastest-growing counties in the nation, with an estimated population of 753,000 -- up 19% from the 2020 census. This growth drives continuous demand for roads, schools, and public safety infrastructure, putting upward pressure on government spending even as rate reductions are pursued.
How Your Williamson County Property Tax Bill Is Calculated
To estimate your bill, take your appraised value, subtract the exemptions you qualify for, and multiply by each entity's rate. Here's a worked example for a Round Rock homeowner with a $420,000 home and the $140,000 school homestead exemption:
| Component | Amount |
|---|---|
| Appraised value | $420,000 |
| Less: School homestead exemption (SB 4 / Prop 13) | -$140,000 |
| Taxable value (school) | $280,000 |
| Round Rock ISD tax ($280,000 x 0.8931%) | $2,501 |
| Williamson County ($420,000 x 0.413776%) | $1,738 |
| City of Round Rock ($420,000 x 0.372%) | $1,562 |
| Total estimated bill | $5,801 |
Remember: The $140,000 school homestead exemption kicks in for 2026 under SB 4 (Proposition 13) and only applies to the ISD portion. The City of Round Rock and Williamson County each offer separate exemptions. Your total bill depends on which entities cover your property and which exemptions you've filed. Learn more about how appraised value, assessed value, and taxable value work.
Why Your Williamson County Property Tax Bill May Be Higher Than Expected
Even if tax rates stay flat or decrease, your bill can increase for several reasons:
Rising Appraisals
The Williamson Central Appraisal District (WCAD) revalues all properties annually. In 2025, the average assessment increase was 6.3%, up from 4.1% in 2024. Newer homes built since 2021 saw the largest increases -- averaging 19.6%. While current values remain roughly 10% below the 2022 peak, the steady recovery is pushing bills higher.
Disaster-Related County Tax Increase
Catastrophic flash floods struck Williamson County on July 5, 2025, triggering disaster declarations from the county, state, and federal government. Under Texas law, taxing entities can use an 8% revenue growth rate (instead of the normal 3.5%) in the year following a disaster declaration. The county used this provision to adopt its 2025 rate of $0.413776 -- a 3.44% increase over the prior year -- without triggering a rollback election.
Municipal Utility Districts (MUDs)
Williamson County has dozens of MUDs, particularly in newer subdivisions. MUD rates vary widely depending on the age of the development -- from $0.25 in mature communities to $1.40 per $100 in new ones. If your property is in a MUD, your total tax rate may exceed 2.5%.
Emergency Services Districts (ESDs)
Properties outside city limits typically fall within an ESD that levies an additional $0.08 to $0.10 per $100 for fire and emergency services. One outlier, ESD #11, levies $0.37 per $100.
How to Lower Your Williamson County Property Taxes
With county rates rising under the disaster revenue cap and WCAD assessments averaging 6.3% higher, Williamson County homeowners should take full advantage of exemptions and the protest process.
1. File for Homestead Exemption
If you haven't filed for your homestead exemption, that's the most straightforward savings available. Beginning in 2026, the school district exemption rises to $140,000 under SB 4 (Proposition 13), saving a typical Round Rock ISD homeowner roughly $1,250 per year in school taxes alone. The City of Round Rock and Williamson County offer their own additional exemptions.
The filing deadline is April 30, and you can file up to two years late to claim missed years.
2. Protest Your WCAD Appraised Value
WCAD's average assessment increase of 6.3% in 2025 -- with newer homes averaging 19.6% -- means many homeowners are likely overvalued. Protesting your Williamson County property tax appraisal lets you present comparable sales and condition evidence to bring your valuation in line with reality. Review your Notice of Appraised Value from WCAD when it arrives in April or May and file a protest before the deadline.
Get Help With Your Williamson County Property Tax Protest
With flood-related county rate increases, rising WCAD assessments, and the Liberty Hill VATRE adding to bills, 2026 is a year where protesting can yield significant savings.
Ballard Property Tax Protest represents homeowners across Williamson County. We handle the entire protest process -- from filing to informal hearings to ARB representation -- and you only pay if we reduce your appraised value.
No reduction, no fee.