26 CFR § 31.6011(a)-5 - Monthly returns.
(a) In general—(1) Requirement. The provisions of this section are applicable in respect of the taxes reportable on returns required pursuant to § 31.6011(a)–1 or § 31.6011(a)–4. An employer (or other person) who is required by § 31.6011(a)–1 or § 31.6011(a)–4 to make quarterly or annual returns on any such form shall, in lieu of making such quarterly or annual returns, make returns of such taxes in accordance with the provisions of this section if the employer is so notified in writing by the IRS. Every employer (or other person) notified by the IRS shall make a return for the calendar month in which the notice is received, for each of the prior calendar months in the return period, and for each calendar month afterwards (whether or not wages are paid in any such month) until the employer has filed a final return or is required to make quarterly or annual returns pursuant to notification as provided in paragraph (a)(2) of this section. Each return required under this section shall be made on the form prescribed for making the return which would otherwise be required of the employer (or other person) under the provisions of § 31.6011(a)–1 or § 31.6011(a)–4, except that, if some other form is furnished by the IRS for use in lieu of such prescribed form, the return shall be made on such other prescribed form. The IRS may notify any employer (or other person)—
(i) Who by reason of notification as provided in § 301.7512–1, is required to comply with the provisions of such § 301.7512–1; or
(ii) Who failed to—
(A) Make any return required pursuant to § 31.6011(a)–1 or § 31.6011(a)–4;
(B) Pay tax reportable on any such form; or
(C) Deposit any such tax as required under the provisions of § 31.6302–1.
(2) Termination of requirement. The IRS, in its discretion, may notify the employer in writing that the employer shall discontinue the filing of monthly returns under this section. If the employer is so notified, the IRS will provide the employer with instructions for filing the final monthly return. Afterwards, the employer shall make quarterly or annual returns in accordance with the provisions of § 31.6011(a)–1 or § 31.6011(a)–4.
(b) Information returns on Form W-3 and Social Security Administration copies of Form W-2. See § 31.6051–2 for requirements with respect to information returns on Form W-3 and Social Security Administration copies of Form W-2.
(c) Time and place for filing returns. For provisions relating to the time and place for filing returns, see §§ 31.6071 (a)–1 and 31.6091–1, respectively.