What follows is an opinion from a United States Court of Appeals.
Intervenors who participated as parties at the courts of appeals should be counted as either appellants or respondents when it can be determined whose position they supported. For example, if there were two plaintiffs who lost in district court, appealed, and were joined by four intervenors who also asked the court of appeals to reverse the district court, the number of appellants should be coded as six.
When coding the detailed nature of participants, use your personal knowledge about the participants, if you are completely confident of the accuracy of your knowledge, even if the specific information is not in the opinion. For example, if "IBM" is listed as the appellant it could be classified as "clearly national or international in scope" even if the opinion did not indicate the scope of the business. 

Your task concerns the first listed respondent. The nature of this litigant falls into the category "federal government (including DC)", specifically "other agency, beginning with "F" thru "N"". Your task is to determine which specific federal government agency best describes this litigant.

Opinion:
Hazel PORTER, Petitioner, v. COMMISSIONER OF INTERNAL REVENUE, Respondent. COMMISSIONER OF INTERNAL REVENUE, Petitioner, v. Hazel PORTER, Respondent.
Nos. 17491, 17505.
United States Court of Appeals Sixth Circuit.
Jan. 18, 1968.
Thomas E. Meister, Cincinnati, Ohio, for Hazel Porter.
Louis M. Kauder, Atty., Dept, of Justice, Washington, D. C., for Commissioner, Mitchell Rogovin, Asst. Atty. Gen., Lee A. Jackson, Robert N. Anderson, Carolyn R. Just, Attys., Dept, of Justice, Washington, D. C., on brief.
Before WEICK, Chief Judge, PHILLIPS, Circuit Judge, and McALLISTER, Senior Circuit Judge.
PER CURIAM.
This is a petition to review a decision of the Tax Court, which held that periodic payments by a husband to his divorced wife over a period of fifteen years pursuant to a divorce decree were taxable to the wife as ordinary income. Reference is made to the memorandum opinion of the Tax Court, T. C. Memo 1966-79, for a complete statement of facts.
It is the claim of the wife that these periodic payments were made to compensate her for her interest in shares of stock in the corporation in which her husband was the principal stockholder and that they did not represent payments for her support.
The wife owned no shares of stock in the corporation, her only relationship with the company being that she formerly had been employed as a secretary. The divorce decree divided other property between the husband and wife but made no mention of the corporate stock. After hearing conflicting evidence the Tax Court made findings of fact that the periodic payments made to the wife were intended to be support payments and did not represent a division of property.
Petitioner contends that the State court’s characterization of the periodic payments as “alimony” does not necessarily mean under Ohio law that they are payments for support, rather than a division of property. The tax consequences of these payments under 26 U.S.C. § 71 are not governed by State law. One of the purposes intended by Congress in enacting this statute was that there would be uniformity of tax treatment for situations arising in the various states. Commissioner of Internal Revenue v. Lester, 366 U.S. 299, 81 S.Ct. 1343, 6 L.Ed.2d 306.
Whether such payments were made to satisfy an obligation to support or to satisfy property rights is a question of intent, and the determination of the Tax Court will not be set aside unless clearly erroneous. Bardwell v. Commissioner of Internal Revenue, 318 F.2d 786 (10th Cir.); Riddell v. Guggenheim, 281 F.2d 836 (9th Cir.).
The decision of the Tax Court is affirmed.

Question: This question concerns the first listed respondent. The nature of this litigant falls into the category "federal government (including DC)", specifically "other agency, beginning with "F" thru "N"". Which specific federal government agency best describes this litigant?

Choices:
Food & Drug Administration
General Services Administration
Government Accounting Office (GAO)
Health Care Financing Administration
Immigration & Naturalization Service (includes border patrol)
Internal Revenue Service (IRS)
Interstate Commerce Commission
Merit Systems Protection Board
National Credit Union Association
National Labor Relations Board
Nuclear Regulatory Commission

Answer: 5