Excess business losses
The TCJA modified existing tax law on excess business losses by limiting losses from all types of business for noncorporate taxpayers.
An excess business loss is the amount by which the total deductions from all trades or businesses exceed a taxpayer’s total gross income and gains from those trades or businesses, plus $250,000, or $500,000 for a joint return.
Excess business losses that are disallowed are treated as a net operating loss carryover to the following taxable year.
See Form 461 and instructions, available soon, for details.
Net Operating Losses
TCJA also modified net operating loss (NOL) rules. Most taxpayers no longer have the option to carryback a NOL. For most taxpayers, NOLs arising in tax years ending after 2017 can only be carried forward. Exceptions apply to certain farming losses and NOLs of insurance companies other than a life insurance company.
For losses arising in taxable years beginning after Dec. 31, 2017, the new law limits the NOL deduction to 80% of taxable income.
Additional updates can be found on the Tax Reform Provisions that Affect Businesses page of IRS.gov.