Section 1.6655-6 - Methods of accounting(a)In general. In computing any required installment, a corporation must use the methods of accounting used in computing taxable income for the taxable year for which estimated tax is being determined (the current taxable year).(b)Accounting method changes. A taxpayer that changes its method of accounting with the consent of the Commissioner for the current taxable year must use the new method of accounting (as of the beginning of the taxable year) in the determination of taxable income for annualization periods ending on or after the date the related section 481(a) adjustment is treated as arising. See § 1.6655-2(f)(3)(ii)(C) for the date a section 481(a) adjustment is treated as arising. If the change in method of accounting does not result in a section 481(a) adjustment, the taxpayer may choose to use the new method of accounting (as of the beginning of the taxable year) in the determination of taxable income for all annualization periods during the year of change or only those annualization periods ending on or after the date the Form 3115 "Application for Change in Accounting Method" was filed with the national office of the Internal Revenue Service. This paragraph (b) only applies to the extent a taxpayer changes a method of accounting for the taxable year with the consent of the Commissioner. Therefore, a taxpayer may be subject to a section 6655 addition to tax for an underpayment of estimated tax if an underpayment results from a change in a method of accounting the taxpayer anticipates making for the taxable year but for which the consent of the Commissioner is not subsequently received.(c)Example. The following example illustrates the rules of this section:(1)Example. Change of accounting method. Corporation ABC, a calendar year taxpayer, uses an accrual method of accounting and the annualization method under section 6655(e)(2)(A)(i) to calculate all of its 2008 required installments. On June 15, 2008, ABC files a Form 3115 requesting permission to change its method of accounting for future litigation reserves for the tax year ending December 31, 2008. On February 15, 2009, ABC receives consent from the Commissioner to make the change for the tax year ending December 31, 2008. The change results in a positive section 481(a) adjustment of $100,000. Under the provisions of § 1.6655-2(f)(3)(ii) ABC chooses to treat the section 481(a) adjustment as arising on the date the Form 3115 is filed with the national office of the Internal Revenue Service. Therefore, ABC is required to use the new method of accounting (as of the beginning of the year) in the determination of taxable income for annualization periods ending on or after June 15, 2008.(d)Effective/applicability date. This section applies to taxable years beginning after September 6, 2007.T.D. 9347, 72 FR 44361 , Aug. 7, 2007, as amended by T.D. 9870, 84 FR 33692 , July 15, 2019 As amended by T.D. 9870, 84 FR 33692, 7/15/2019