法第二条第一項第十三号に規定する政令で定める一定の期間は、公共法人等（国、地方公共団体その他法人税法第十三条及び第十四条（事業年度）の規定の適用を受けない法人（人格のない社団等を含む。以下同じ。）をいう。以下この条において同じ。）の会計年度その他これに準ずる期間（以下この条において「会計年度等」という。）で、法令で定めるもの又は公共法人等の定款、寄附行為、規則若しくは規約（以下この条において「定款等」という。）に定めるものとし、法令又は定款等に会計年度等の定めがない場合には、次項の規定により納税地を所轄する税務署長に届け出た会計年度等又は第三項の規定により納税地を所轄する税務署長が指定した会計年度等若しくは第四項に規定する期間とする。ただし、これらの期間が一年を超える場合は、当該期間をその開始の日以後一年ごとに区分した各期間（最後に一年未満の期間を生じたときは、その一年未満の期間）とする。
The fixed period specified by Cabinet Order prescribed in Article 2, paragraph (1), item (xiii) of the Act is to be the fiscal year of a public corporation, etc. (meaning the national government, a local government, or any other corporation not subject to the application of Articles 13 and 14 (Business Year) of the Corporation Tax Act (including an association or foundation without legal personality; the same applies hereinafter); the same applies hereinafter in this Article) or any other period equivalent to it (hereinafter in this Article referred to as the "fiscal year, etc.") that is prescribed by laws and regulations, or that is prescribed in the articles of incorporation, act of endowment, rules or regulations of the public corporation, etc. (hereinafter in this Article referred to as the "articles of incorporation, etc."), and, where laws and regulations or the articles of incorporation, etc. do not prescribe a fiscal year, etc., is to be the fiscal year, etc. notified to the district director having jurisdiction over the place for tax payment under the provisions of the following paragraph, the fiscal year, etc. designated by the district director having jurisdiction over the place for tax payment under the provisions of paragraph (3), or the period prescribed in paragraph (4); provided, however, that where any of those periods exceeds one year, it is to be each period into which that period is divided at intervals of one year from its start date (or, where a period of less than one year arises at the end, that period of less than one year).