This is a rather specific question, but I'm wondering if others who have used IRS data have encountered this oddity. I'm looking at the IRS Statistics of Income for individuals here, specifically the most recent Publication 1304 Table 1.2.
This table has the data broken down by the level of adjusted gross income. The first such group is listed as "No adjusted gross income". Under the "All returns" section, the column for "Total income tax" shows 177,444; since it says money amounts are in thousands, this would be $177,444,000. But the "number of returns" column shows only 6231 returns. This comes out to an average of more than $28,000 in tax paid per return, which is far more than the corresponding numbers for other income levels until you get to $100k+ AGI.
Why does this IRS data seem to show that people with zero income were paying an average of $28,000 in taxes? Am I missing something about how to interpret these values?