D.C. Mun. Regs. tit. 9, r. 9-332
The income and expense form, with accompanying attachments and documents, shall be electronically submitted to the Deputy Chief Financial Officer on or before 11:59 PM of April 15th of the year in which written notice of a filing requirement of such form is mailed to the affected taxpayer. Electronic submission shall require the use of the appropriate and approved forms and document upload and submission functions available through the Deputy Chief Financial Officer's website portal.
Written notice of a filing requirement of the income and expense form shall be mailed by the Deputy Chief Financial Officer to the affected taxpayers at least thirty (30) days prior to the due date provided in § 332.1. Such notice shall state where and how the appropriate income and expense form may be found and filed.
When, in the opinion of the Deputy Chief Financial Officer, an income and expense form submitted prior to the deadline set forth in § 332.1 has not been accurately completed (that is, it is either inaccurate or incomplete, or both), the Deputy Chief Financial Officer shall inform the affected taxpayer (or the taxpayer's agent) as soon as possible and request, in writing, that the form be accurately completed and delivered not later than thirty (30) days from the date of the mailing of the notice or as otherwise specified.
Extensions of time, not to exceed thirty (30) days, to submit the forms may be granted at the discretion of the Deputy Chief Financial Officer for good cause.
A request for an extension to file shall be delivered to the Deputy Chief Financial Officer not later than April 1st of the year in which the forms are to be mailed to affected taxpayers. Requests for extensions delivered after April 1st shall not be granted.
D.C. Mun. Regs. tit. 9, r. 9-332