Fiscal Year (FY)
A fiscal year (FY) is a 12 month period of time, or accounting year, used by governments, businesses, organizations, and individuals for accounting purposes. It is not necessarily the same as a calendar year.
The federal government uses a fiscal year for accounting purposes that begins on October 1st and ends on September 30th.
U.S. Senate Definition
fiscal year - The fiscal year is the accounting period for the federal government which begins on October 1 and ends on September 30. The fiscal year is designated by the calendar year in which it ends; for example, fiscal year 2013 begins on October 1, 2012 and ends on September 30, 2013. Congress passes appropriations legislation to fund the government for every fiscal year.