Short year and 40 percent tax rule
Short years are fiscal years that are shorter than the originally-specified
fiscal year.
You must use the short year-end close procedure, instead of the normal year-end closing procedure when the fiscal year for your company must be revised and ended earlier than previously specified. The 40% tax rule is a United States tax ruling that applies to depreciation calculations after at least 40 percent of a company's assets that are placed in service during a fiscal year have been added during the last fiscal quarter.
Consult your tax advisor for more information.