I've been fighting my taxes every year for the past four years. I've always been able to get the appraised value reduced. The first couple of years I was able to get it reduced just using the online protest. Last year, the online protest didn't get a reduction. But, I was able to get what I wanted by meeting with one of the appraisers. My advice is to find homes with a similar class or better in the same neighborhood with similar lot size or bigger that have lower tax $/sqft. Then use these as your comps pointing out the inequity of values.
I will say, that it appears that if you do fight your taxes and win, they seem to come back and hit you harder the next year. Last year they hit me with an almost 10% increase and I was able to get that down to less than 2% increase. This year, they hit me with a 30% increase, which is the second highest increase in my entire neighborhood.
Anyway... last year when I protested, I obtained a copy of the class code. If you ask them for it, they will give you a copy. Here's a summary taken from the "Brazos Central Appraisal District Residential Cost Guide, General Guidelines for Residential Classification"...
R - Residential
V - Exterior is masonry type: Brick, Block, and/or stone
F - Exterior is wood type, Wood, Hardy Plank, Stucco, Vinyl, Asbestos and/or Cement board.
P - Plus. This represents an addition to the classification when a home does not fit within the boundaries of two independent classes, therefore a "P (Plus) factor" is applied. For instance, when a lower class is too low of quality for the home and the next highest class is too high of quality a P factor would be applied. It is also used when a home is exceptional or inferior for its class.
1-9 P= Numerical classification is in order of quality, i.e. 1= Lowest Quality and 9P = Highest Quality
The phrases they have associated with each...
RV1, RV1P, RF1, RF1P: Substandard Quality
RV2, RV2P, RF2, RF2P: Low Quality
RV3, RV3P, RF3, RF3P: Fair Quality
RV4, RV4P, RF4, RF4P: Average Quality
RV5, RV5P, RF5, RF5P: Above Average Quality
RV6, RV6P, RF6, RF6P: Good Quality
RV7, RV7P, RF7, RF7P: Excellent Quality
RV8, RV8P, RF8, RF8P: Outstanding Quality
RV9, RV9P, RF9, RF9P: Extravagant/Luxury Quality
The set of guidelines does include a more detailed description for each level and include sample floor plans and pictures.
Hope this helps some of you out. Good luck!