Under pre-Act law, a net operating loss (NOL) may generally be carried back two years and carried over 20 years to offset taxable income in such years. However, different carryback periods apply with respect to NOLs arising in different circumstances. For example, extended carryback periods are allowed for NOLs attributable to specified liability losses and certain casualty and disaster losses.

New law. For NOLs arising in tax years ending after Dec. 31, 2017, the two-year carryback and the special carryback provisions are repealed, but a two-year carryback applies in the case of certain losses incurred in the trade or business of farming.

For losses arising in tax years beginning after Dec. 31, 2017, the NOL deduction is limited to 80% of taxable income (determined without regard to the deduction). Carryovers to other years are adjusted to take account of this limitation, and, except as provided below, NOLs can be carried forward indefinitely.

However, NOLs of property and casualty insurance companies can be carried back two years and carried over 20 years to offset 100% of taxable income in such years.