A net operating loss (NOL) happens when a company’s deductions exceed its taxable income. It can help by reducing their taxable income in future tax years.
For tax years prior to 2018, they can still claim the 2-year carryback rule.
Due to the Tax Cuts and Jobs Act (TCJA), this was eliminated for future tax years except for specific farming losses and NOLs of insurance companies other than life insurance. There is now an indefinite carryforward period. However, these carryforwards are now limited to 80% of income.