A special type of tax-deductible loss, similar to a casualty loss, where a loss has been incurred by taxpayers who reside in an area that has been designated as a federal disaster area by the President. Disaster losses can arise from such phenomena as floods, forest fires and earthquakes.

Disaster losses may be deducted either in the year that the loss is incurred or the previous year, if it is more beneficial to the taxpayer and pending on the type of disaster. Homeowners who must relocate due to damage in a disaster area can often claim a loss even though the damage sustained does not meet the sudden event test.