The term "business year" as used in this Act means a period that serves as the unit for calculating the property and profit and loss of a corporation (hereinafter referred to as an "accounting period" in this Chapter) which is specified by laws and regulations or specified in the articles of incorporation, act of endowment, rules, bylaws or other equivalent instruments of the corporation (hereinafter referred to as the "articles of incorporation, etc." in this Chapter), and, where no accounting period is specified by laws and regulations or in the articles of incorporation, etc., means the accounting period notified to the competent district director with jurisdiction over the place for tax payment pursuant to the provisions of the following paragraph, or the accounting period designated by the competent district director with jurisdiction over the place for tax payment pursuant to the provisions of paragraph (3) or the period prescribed in paragraph (4); provided, however, that where any of these periods exceeds one year, it means each of the periods into which the period on or after its first day is divided every one year (where a period of less than one year remains at the end, that period of less than one year).
この法律において「事業年度」とは、法人の財産及び損益の計算の単位となる期間（以下この章において「会計期間」という。）で、法令で定めるもの又は法人の定款、寄附行為、規則、規約その他これらに準ずるもの（以下この章において「定款等」という。）に定めるものをいい、法令又は定款等に会計期間の定めがない場合には、次項の規定により納税地の所轄税務署長に届け出た会計期間又は第三項の規定により納税地の所轄税務署長が指定した会計期間若しくは第四項に規定する期間をいう。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）をいう。
A corporation for which no accounting period is specified by laws and regulations or in its articles of incorporation, etc. must set an accounting period and notify the competent district director with jurisdiction over the place for tax payment thereof within two months on or after the day specified in the following items for the category of corporation listed in each of those items:
domestic corporation: the date of its establishment (for the corporations listed below, the day specified respectively below);
内国法人 設立の日（次に掲げる法人については、それぞれ次に定める日）
a public interest corporation, etc. or an association or foundation without juridical personality that has newly commenced a profit-making business: the date on which it commenced that business;
a public interest corporation, etc. conducting a profit-making business that was a public service corporation: the date on which it became that public interest corporation, etc.;
an ordinary corporation or a cooperative, etc. that was a public service corporation or a public interest corporation, etc. not conducting a profit-making business: the date on which it became that ordinary corporation or cooperative, etc.
foreign corporation: the date on which it became a foreign corporation that has a permanent establishment, or the date on which, without having a permanent establishment, it commenced in Japan the business prescribed in Article 138, paragraph (1), item (iv) (Domestic Source Income) or came to have domestic source income specified in Article 141, item (ii) (Tax Base) other than the consideration listed in item (iv) of Article 138, paragraph (1) (for an association or foundation without juridical personality, the date on which it came to have, out of the domestic source income specified in each item of Article 141 for the category of foreign corporation listed in the relevant item, the income arising from a profit-making business).
In the case where a corporation (excluding an association or foundation without juridical personality) that is required to give notification under the provisions of the preceding paragraph fails to give the notification, the competent district director with jurisdiction over the place for tax payment is to designate its accounting period and notify the corporation thereof in writing.
In the case where an association or foundation without juridical personality that is required to give notification under the provisions of paragraph (2) fails to give the notification, the accounting period of the association or foundation without juridical personality is to be the period from January 1 of each year (for the year that includes the day specified in item (i), (a) of that paragraph or the day on which it came to have domestic source income prescribed in item (ii) of that paragraph that arises from a profit-making business, from that day) through December 31.