(a) Requirement of declaration. No declaration may be made for a period of more than 12 months. For purposes of this section a taxable year of 52 or 53 weeks, in the case of a corporation which computes its taxable income in accordance with the election permitted by section 441(f), shall be deemed a period of 12 months. For special rules affecting the time for filing declarations and paying estimated tax by such corporation, see paragraph (b) of § 1.441-2. A separate declaration is required where a corporation is required to submit an income tax return for a period of less than 12 months, but only if such short period ends on or after December 31, 1955. However, no declaration is required if the short taxable year:

(1) Begins on or before December 31, 1963, and is:

(i) A period of less than 9 months, or

(ii) A period of 9 or more months but less than 12 months and the requirements of section 6016(a) are not met before the 1st day of the last month in the short taxable year, or

(2) Begins after December 31, 1963, and is:

(i) A period of less than 4 months, or

(ii) A period of 4 or more months but less than 12 months and the requirements of section 6016(a) are not met before the 1st day of the last month in the short taxable year.

(b) Income placed on an annual basis. In cases where the short taxable year results from a change of annual accounting period, for the purpose of determining whether the anticipated income for a short taxable year will result in an estimated tax liability requiring the filing of a declaration, such income shall be placed on an annual basis in the manner prescribed in section 443(b)(1). If a tax computed on such annualized income exceeds the sum of $100,000 and any credits under part IV, of subchapter A, chapter 1 of the Code, the estimated tax shall be the same part of the excess so computed as the number of months in the short period is of 12 months. Thus, for example, a corporation which changes from a calendar year basis to a fiscal year basis beginning October 1, 1956, will have a short taxable year beginning January 1, 1956, and ending September 30, 1956. If on or before August 31, 1956, the taxpayer anticipates that it will have income of $264,000 for the 9-month taxable year the estimated tax is computed as follows: