From the IRS brief:
The President has declared that a major disaster exists in the State of Mississippi. Following the recent disaster declaration for individual assistance issued by the Federal Emergency Management Agency, the IRS announced today that affected taxpayers in Mississippi will receive tax relief.
Individuals who reside or have a business in Forrest, Lamar, Lauderdale, and Perry Counties may qualify for tax relief.
The declaration permits the IRS to postpone certain deadlines for taxpayers who reside or have a business in the disaster area.