As indicated, we estimate that un-collected sales taxes on state and local sales in 2008 totaled approximately $3.9 billion, slightly more than half of what is estimated by the Fox Study. Over the course of the five-year period from 2008-2012, our estimates diverge still further from those of the Fox Study. For example, the Fox Study estimates un-collected revenues could be as high as $12.7 billion in 2012, compared with our estimate of $4.7 billion.