Under U.S. Federal income tax law, a net operating loss (NOL) occurs when certain tax-deductible expenses exceed taxable revenues for a taxable year.[1] If a taxpayer is taxed during profitable periods without receiving any tax relief (e.g., a refund) during periods of NOLs, an unbalanced tax burden results.[2] Consequently, in some situations, Congress allows taxpayers to use the losses in one year to offset the profits of other years.