Here are some resources on protesting your home's tax appraisal value and taxes.
County websites on protesting taxes:
Hays Central Appraisal District
Travis Central Appraisal District
Mailed property tax appraisal amounts (Notice of Appraised Value) should have been received and/or mailed by now. It estimates the taxable value of your home and estimates of your county, city, and school district taxes. "The deadline to file your protest is May 15 or 30 days after your Notice is mailed, whichever is later" for Travis County and most other counties.
The notice tells you when and how to protest the value. If you need help finding your home's legal description or finding sold comps to help you protest your value, let me know. I offer this service for past clients. Just give me a few days to provide such info.
I personally hire a company to protest for me as this is a (somewhat) complicated and specialize field of work. Nevertheless, I have neighbors that protest things themselves. Not sure how successful they are at doing so. 😄 You might try the informal process. Moreover, remember the legislature occassionally changes the law on tax appraisals.