T aid the user with interpreting

and should not be construed as interpretations of the Internal Revenue (IR) Code or policies of the Internal Revenue Service (IRS). Code sections cited are those in effect for the tax years covered in this report. The tax year refers to the calendar year, unless otherwise stated. The line references given for the terms correspond to Form 1120, U.S. Corporation Income Tax Return, unless otherwise indicated. In most tables, items taken from other forms (1120-L, 1120-F, etc.) and attached schedules conform to the Form 1120 format. Although many standardizing adjustments were made, the data presented are unaudited as reported by taxpayers and are, therefore, subject to taxpayer errors and misinterpretations, as well as statistical variability and any errors that may have arisen during processing. (See “Data Limitations and Measures of Variability” in Section 3.) In addition, any definitions marked with the symbol Δ have been revised for 2022 to reflect changes in the law.

Accounting Periods

Data were classified according to the ending dates of the accounting periods covered by the corporations’ income tax returns. Returns were generally filed covering an annual accounting period—most larger corporations filed returns for accounting periods ending in December (a calendar-year period), while some corporations filed “part-year returns,” which cover a shorter accounting period (less than 1 year). Corporations filed part-year returns because of business organizations or reorganizations, mergers, liquidations, or changes to accounting periods. The statistics include income and tax data from part-year returns, but do not include balance sheet data. (See “Balance Sheets.”)

Figure D in Section 1 shows the number of returns filed for each accounting period covered in this report. For a discussion of this classification, see “Time Period Employed” in Section 1, Introduction.