Certified Medical Administrative Assistants (CMAA) Practice Exam 2025 - Free CMAA Practice Questions and Study Guide

The nine-digit number specifically used for federal tax accounting purposes is the Employer Identification Number (EIN). This number is assigned by the Internal Revenue Service (IRS) to identify businesses, including corporations, partnerships, and non-profit organizations. An EIN serves primarily for tax administration and is necessary for a business to open a bank account, hire employees, and file tax returns.

The other options, while related to tax and identification, do not exclusively serve the federal tax accounting purpose in the same capacity as an EIN. A Taxpayer Identification Number (TIN) can refer to various identification numbers used by the IRS in tax processing, which might include an EIN, but it is a broader term and can also include Individual Taxpayer Identification Numbers (ITINs). The Social Security Number (SSN) is mainly issued to individuals for personal identification and taxes but is not exclusively for businesses. Lastly, a Business License Number is issued by local jurisdictions for the operation of a business and does not have relevance to federal tax accounting. Thus, the EIN is precisely designed for that federal tax accounting functionality.