According to people who have seen Sky's response, the report questions whether or not Ofcom has the right to rule on the case.
It also says that the methodology used to calculate the amount that it can charge is flawed.
BSkyB's chief operating officer Mike Darcey told the Financial Times: "This is a case that tests the outer limits of Ofcom's powers. If it comes to it we'll look forward to getting an impartial hearing before a court."
Ofcom said earlier this year that Sky would have to charge less to rivals for broadcasting content after a lengthy review of the pay-TV market, which was triggered by complaints by Sky's rivals, including Virgin Media and BT Vision.
A three-month consultation period to allow for responses to the proposals finishes this month.