D.C. Mun. Regs. tit. 9, r. 9-327
The Deputy Chief Financial Officer shall make every effort to afford affected taxpayers the opportunity to apply and qualify for mixed use status, but it shall be the affected taxpayer's responsibility to inform the Deputy Chief Financial Officer of the existence of a mixed use property by properly completing and timely filing the mixed use form. The classes of property for tax purposes are set forth in D.C. Code § 47-813 and § 9903 of this title.
For the purposes of this chapter, an "affected taxpayer," is an owner of real property in the District who is required to file a mixed use form in accordance with the provisions of this section.
If any mixed use form is not sub mitted to the Deputy Chief Financial Officer on or before September 1st of the year in which such forms ar e mailed or made electronically available to affected taxpayers on the OTR online portal, in the discretion of the Deputy Chief Financial Officer, or within the time extended by the Deputy Chief Financial Officer, or any mixed use form is timely submitted on or before September 1st, but is either inaccurate or incomplete and, after written or electronic notice from the Deputy Chief Financial Officer and, in the opinion of the Deputy Chief Financial Officer, remains inaccurate or incomplete, the Deputy Chief Financial Officer shall classify the affected taxpayer's real property as Class 2 Property for the next taxable year (October 1s t - September 30th), subject to the property being classified as Class 3 or Class 4.
The Deputy Chief Financial Officer shall notify affected taxpayers of Class 2 Property status which results because of the application of § 327.3 through the billing process or by any other method which is deemed appropriate.
Whenever the mixed use form or information sought under the form, or records or documents sought to completely and accurately inform the Deputy Chief Financial Officer as to the mixed use of the property are not submitted in the time provided for by this chapter, and it is shown to the Deputy Chief Financial Officer's satisfaction that the failure to provide the form, information, record, or document was due to reasonable cause and was not due to simple neglect, the Deputy Chief Financial Officer shall apportion the mixed uses of the property according to the best information available.
D.C. Mun. Regs. tit. 9, r. 9-327