If you feel your appraised value is too high, compared to the market value of your home, you can argue the value. You can hire a company that does this for you or you can do it yourself. If you would like to do it yourself, get recent sold information and take it to the district office. You may only do this during the first few months of the year. I am a Realtor in Houston and send my clients comparable sold prices if their appraised values are too hign.
Change the property value not clear on your question you need to submit documents OR petition county change the value.
Contact the county office resolve all of your questions they are experts who handle these issues.
Lynn911 Dallas Realtor & Consultant, Loan Officer, Credit Repair Advisor
The Michael Group - Dallas Business Journal Top Ranked Realtors