(b)
If a return of such income has been made, then the following data in respect of such return:
(1) The taxable year for which the return was made and the tax paid;
(2) The name of the taxpayer for whom the return was made;
(3) The name of the agent or other person (if any) by whom such return was made;
(4) The office of the district director in which the return was filed.
(c) Such other facts as may be required, from time to time, by the Commissioner.
(ii) Other taxes. Except as otherwise provided in subdivision (i) of this subparagraph, in order to make a final computation of the amount of any internal revenue tax payable by return in any case, the usual return should be filed, together with the supporting documents required by the regulations pertaining to the tax.
(g) Tax returns—(1) General. In many cases allowance of deductions and credits is contingent upon the making of a return in accordance with the applicable internal revenue law. The submission of evidence relative to income tax in accordance with subdivisions (a) and (c) of paragraph (f)(2)(i) of this section will be considered as the making of the return required by any such law, only (i) for any taxable period, ending on or before December 31, 1946, during all or part of which all or part of the property of the taxpayer was held by the Attorney General, or (ii) for any taxable period ending within one year from the date of the first return to the taxpayer, of any part of the property held by the Attorney General, whichever period ends later. In all other cases a return will be required in accordance with the applicable internal revenue laws and regulations. In the case of returns where property is vested during a taxable year or period, see paragraph (d) of this section.
(2) Estates and trusts. In the case of estates and trusts the fiduciaries shall file returns, including information returns as required by section 6041 of the Internal Revenue Code of 1954.
(3) Income tax forms to be used. In the case of taxpayers engaged in trade or business in the United States Forms 1040B and 1120, as may be appropriate, shall be used. Where the taxpayer is not engaged in trade or business in the United States, Form M797 may be used in lieu of Forms 1040NB, 1040NB-–a and 1120NB.
Source
26 CFR § 303.1-4
Scoping language
Detail of employees of the Internal Revenue Service. The Commissioner will detail for the assistance of the Attorney General such employees of the Internal Revenue Service as may be necessary to make the computations under this part promptly and accurately.