A document published by the Internal Revenue Service (IRS) that provides guidance to individuals who have more deductions than income in a given tax year. If the total deductions a taxpayer claims are greater than that taxpayer's income for the year, the taxpayer is said to have a net operating loss (NOL). The NOL loss is typically caused by deductions related to business expenses, casualty or theft, moving expenses, rental property expenses or expenses related to being an employee.

To determine if there is a NOL, individual taxpayers should first complete their tax return. A negative number appearing in line 41 (in form 1040) or line 38 (in form 1040NR) may mean that there is a NOL. Taxpayers then must determine if the NOL is carryfoward, carryback or is to be used in the current tax year.

IRS Publication 536 does not cover bankruptcies or losses incurred by partnerships or S Corporations, though individual partners or S corporation shareholders can use the income or deductions from their personal shares in order to calculate their individual NOL.