26 U.S.C. § 6041: Information at source

All persons engaged in a trade or business and making payment in the course of such trade or business to another person, of rent, salaries, wages, premiums, annuities, compensations, remunerations, emoluments, or other fixed or determinable gains, profits, and income (other than payments to which section 6042(a)(1), 6044(a)(1), 6047(e), 6049(a), or 6050N(a) applies, and other than payments with respect to which a statement is required under the authority of section 6042(a)(2), 6044(a)(2), or 6045), of $2,000 or more in any calendar year, or, in the case of such payments made by the United States, the officers or employees of the United States having information as to such payments and required to make returns in regard thereto by the regulations hereinafter provided for, shall render a true and accurate return to the Secretary, under such regulations and in such form and manner and to such extent as may be prescribed by the Secretary, setting forth the amount of such gains, profits, and income (including a separate accounting of any such amounts reasonably designated as cash tips and the occupation described in section 224(d)(1) of the person receiving such tips and a separate accounting of any amount of qualified overtime compensation (as defined in section 225(c))), and the name and address of the recipient of such payment. In the case of collections of items (not payable in the United States) of interest upon the bonds of foreign countries and interest upon the bonds of and dividends from foreign corporations by any person undertaking as a matter of business or for profit the collection of foreign payments of such interest or dividends by means of coupons, checks, or bills of exchange, such person shall make a return according to the forms or regulations prescribed by the Secretary, setting forth the amount paid and the name and address of the recipient of each such payment. When necessary to make effective the provisions of this section, the name and address of the recipient of income shall be furnished upon demand of the person paying the income. the name, address, and phone number of the information contact of the person required to make such return, the aggregate amount of payments to the person required to be shown on the return, in the case of compensation to non-employees, the portion of payments that have been reasonably designated as cash tips and the occupation described in section 224(d)(1) of the person receiving such tips, and the portion of payments that are qualified overtime compensation (as defined in section 225(c)). This section shall not apply to tips with respect to which section 6053(a) (relating to reporting of tips) applies. a flexible spending arrangement (as defined in section 106(c)(2)), or a health reimbursement arrangement which is treated as employer-provided coverage under an accident or health plan for purposes of section 106. any deferrals for the year under a nonqualified deferred compensation plan (within the meaning of section 409A(d)), whether or not paid, except that this paragraph shall not apply to deferrals which are required to be reported under section 6051(a)(13) (without regard to any de minimis exception), and any amount includible under section 409A and which is not treated as wages under section 3401(a). such dollar amount, multiplied by the cost-of-living adjustment determined under section 1(f)(3) for such calendar year, determined by substituting “calendar year 2025” for “calendar year 2016” in subparagraph (A)(ii) thereof. without regard to Revenue Rulings 75–400 and 76–231, and in accordance with the manner in which such law was administered before the issuance of such rulings. This section shall take effect on January 1, 1976 .”