Generally, the tax loss does is not required to be calculated with precision. Technically, the court needs only to make a “reasonable estimate” of loss the defendant intended to inflict as opposed to actual loss. However, there are guidelines that direct the calculation of tax loss for specific tax crimes. For unreported income, the tax loss is equal to 28% of unreported gross income (34% for corporations) plus 100% of false credits claimed. For claiming a false deduction or exemption, the tax loss is equal to 28% of the improperly claimed deduction or exemption (34% for corporations) plus 100% of any false credits claimed. Tax loss of a charge for failure to file a return is 20% of the gross income (25% for corporations) less tax withheld or otherwise paid.
Where tax loss is not reasonably ascertainable, the above presumptions are used unless the government or defense has sufficient information for a more accurate determination. Tax loss does not ordinarily include interest or penalties, except in willful evasion of payment under IRC §7201 and willful failure to pay under IRC §7203 cases. The tax loss computation does include the tax associated with an offense or conviction and any relevant conduct, including acquitted or dismissed charges. For purposes of this provision, relevant conduct means the same course of criminal conduct or common scheme or plan connected by at least one common factor (i.e. victims, accomplices, purpose, similar modus operandi).