Get your taxes done using TurboTax

You enter two line items.  1 showing the 1099K information  (example: $1500 in income)

then on the next line you enter the exact same Verbiage but enter your Cost in a negative entry... (example: -1300.00  This will give you a reported income of $200... (1500 - 1300 = 200).  hope this helps!