Short answer is Yes.  Longer answer is Rarely Happens.The ARB is the only authority that can raise a proposed (or "Notice") market value after it's published by the Chief Appraiser on or before May 1.  In our experience it has happened only once and that was because our client misled us.  Here's what happened.  Our client purchased the property for $2,000,000 which was far above the market based on comparable sales and specified that MLS not disclose the price paid.  The district, seeing a non disclosed price, proposed a value in excess of what it felt the market would support -- but less than the $2,000,000 purchase price.  (Obviously the owner paid above market for personal reasons.)  Appraisal districts often do this to "smoke out" a protest at which the taxpayer (or agent) will be asked to produce the Settlement Statement.  If there's no statement produced then obviously there's no case for a reduction.In cases like that where we don't have candid information and it looks like the ARB panel is unhappy with the taxpayer's secrecy, we will withdraw the protest before the hearing is closed to testimony, thus preventing the panel from raising the proposed value.  But where the taxpayer -- our client -- doesn't level with us there's always a risk that the ARB panel, confronted with a non disclosed price and a taxpayer unwilling to be candid, will close the hearing without warning and raise the district's proposed value.  It can happen especially where an owner is self represented or where an agent is not experienced.  Experience counts. Lesson here is that if you are candid with us as your agent, we can protect you from unwanted surprises.