If the IRS becomes suspicious about your taxes and starts investigating you for tax evasion or tax fraud they can impose a civil tax fraud penalty which is equal to 75% of the tax owed plus interest on the penalty. They also can decide to send the case to the IRS Criminal Investigation unit for criminal tax prosecution. There are penalties associated with these frauds! They can range from spending time in the penitentiary to paying excessive fines, neither of which you want to do! It is in your best behalf to seek the help of a tax attorney.