Williamson County Property Tax Estimator
2025 rates for every Williamson County city, school district and special district, preloaded. Pick your units, enter your value.
Short answer: Williamson County's rate is 0.413776%. A $400,000 homestead in Round Rock pays about $5,465.16 a year at a combined 1.678876%.
Build your estimate
| Taxing unit | Rate | Exemption | Taxable value | Tax |
|---|
Williamson County example
To match it, pick Round Rock and Round Rock ISD, enter $400,000 and choose homestead: yes.
- Williamson County $1,655
- Round Rock $1,488
- Round Rock ISD $2,322
| Unit | Taxable | Rate | Tax |
|---|---|---|---|
| Williamson County | $400,000 | 0.413776%$0.413776 per $100 | $1,655.10 |
| Round Rock | $400,000 | 0.372%$0.372 per $100 | $1,488.00 |
| Round Rock ISD | $260,000 | 0.8931%$0.8931 per $100 | $2,322.06 |
| Total | 1.678876%$1.678876 per $100 | $5,465.16 |
- Appraisal district: Williamson Central Appraisal District (WCAD)
- Protest deadline: May 15 (next business day if that falls on a weekend), or 30 days after the notice is mailed — whichever is later (Tax Code §41.44). Check your notice.
Questions
What is the Williamson County property tax rate?
Williamson County's own 2025 rate is 0.413776% ($0.413776 per $100). Cities add 0.151118% to 0.84% and school districts 0.861% to 1.2389%, so your total depends on your address.
How much is property tax on a $400,000 home in Round Rock?
About $5,465.16 a year for a homestead, at a combined 1.678876% (Williamson County, Round Rock, Round Rock ISD), after the $140,000 school homestead exemption and before any local optional exemptions.
What exemptions does the estimator apply?
Only the state school-district homestead exemption: $140,000, or $200,000 if you are 65+ or disabled. County, city and special-district exemptions vary by unit and are not assumed.
Where do I find my exact taxing units in Williamson County?
Look up your property on Williamson Central Appraisal District (WCAD). Your account lists every unit that taxes it, including MUDs and ESDs.