Also, since the "sporadic contract work" is self-employment income in the eyes of the IRS, they are required to file a tax return since the amount of self-employment income earned was more than $400. While they will not pay "regular" tax on their total income for the tax year since it was less than $12,400, they will definitely pay the 15.3% self-employment tax on the $3,200 earned while self-employed.
Note that the $3,200 will be reported on SCH C where they can deduct any business related expenses from that amount, thus reducing the amount of self-employment income they have to pay that 15.3% SE tax on.
