In general, taxable income is required to be computed under the method of accounting used by a taxpayer in maintaining its books, except as otherwise required by the Internal Revenue Code (IRC or Code) or Treasury regulations (IRC §446(a)). Consequently, a taxpayer that consistently applies generally accepted accounting principles (GAAP) in computing its income from a business for purposes of its financial statements ordinarily will use that same method in computing its taxable income. If, however, that method "does not clearly reflect income," the computation of taxable income must be made under such method as, in the opinion of the Commissioner, does clearly reflect income (IRC §446(b)).