If you believe that the County's value does not reflect the fair market value of your property as of January 1st, you should appeal. The appeals process is an opportunity to review a property in more detail.
You have two opportunities to appeal. The first opportunity is when you receive your property's "Valuation Notice" in the spring (generally in March). This is known as an "Informal Meeting." The second opportunity is when you receive your tax statement in late November. This appeal is known as a "Payment Under Protest."