Fiscal Year:

A fiscal year (or financial year, or sometimes budget year) is a period used for calculating annual ("yearly") financial statements in businesses and other organizations. In many jurisdictions, regulatory laws regarding accounting and taxation require such reports once per twelve months, but do not require that the period reported on constitutes a calendar year (i.e., January through December). Fiscal years vary between businesses and countries.
In addition, many companies find that it is convenient for purposes of comparison and for accurate stock taking to always end their fiscal year on the same day of the week, where local legislation permits. Thus some fiscal years will have 52 weeks and others 53.