The informal tax assessment appeals for Allegheny County will begin in January, 2012. Don't be fooled into thinking the process is not important.  In fact, it can be very important to correcting errors concerning the market value of your property and the resulting tax bill.  Make sure you are prepared to talk about the value units of comparison such as living area square feet, above ground living area, lot size, location land value differences, depreciation etc. For commercial and industrial properties it is even more complicated...