Federal spending allocated outside of the regular appropriations cycle, often due to an emergency such as a natural disaster or war.
Unlike other federal spending approved by Congress during the annual appropriations process, supplemental appropriations fund emergency spending on an ad hoc basis for matters too urgent to postpone until the next fiscal year. Because of their exigent nature, supplemental appropriations have not historically attracted the intense scrutiny of regular appropriations and are not subject to congressional budget controls. Supplemental appropriations have been used in recent years to fund the wars in Iraq and Afghanistan, improve border security, and combat the Ebola and Zika outbreaks. Disaster relief is another common use of supplemental appropriations.
Emergency and disaster declarations are made at a governor's request and must be approved by the president. A disaster declaration triggers federal emergency relief resources under the Stafford Act of 1988. The FEMA-administered Disaster Relief Fund (DRF) is only equipped to handle disasters costing less than $500 million. Large disasters quickly deplete these funds and thus prompt the need for additional funding through supplemental appropriations.
The federal response to natural disasters has become more political in recent years. President George W. Bush was widely criticized for his administration's slow response to Hurricane Katrina in 2005, and Congress struggled to pass disaster relief for Northeastern states following Hurricane Sandy in 2012.
With the historic 2017 hurricane season having already caused widespread devastation to the U.S. mainland, Puerto Rico, and the US Virgin Islands, supplemental appropriations will be necessary to support those recovery efforts. To counter conservative criticism of the inclusion in relief bills of unrelated spending, Congress is expected to take up several incremental relief packages instead of one massive spending bill. Congress already provided $15 billion in supplemental appropriations in response to Hurricane Harvey, which is a down payment on the overall expected spending on Hurricanes Harvey, Irma, and Maria combined. The Trump Administration is expected to submit an official disaster relief request to Congress in October, which will be the next step for a second supplemental appropriations bill for hurricane relief.