D.C. Mun. Regs. tit. 9, r. 9-905
In the absence of records showing the number of miles actually operated per gallon of motor fuel, it shall be conclusively presumed that the average mileage so operated by the bus in all operations, within or without the District, during the tax period, was four (4) miles per gallon.
If a report required to be filed under the Act is not filed, or if a report when filed is incorrect or insufficient, the amount of tax due shall be determined by the Deputy Chief Financial Officer from such information as may be obtainable. Written notice of the determination shall be mailed to the taxpayer by registered mail or by certified mail.
A determination under § 905.2 shall finally and irrevocably fix the tax unless the person against whom it is assessed applies in writing to the Deputy Chief Financial Officer for a hearing within thirty (30) days after the mailing date of the notice of the determination; or unless the Deputy Chief Financial Officer, on his or her own motion, redetermines the amount.
After a hearing or redetermination, the Deputy Chief Financial Officer shall give notice of the final determination to the person against whom the tax is assessed.
D.C. Mun. Regs. tit. 9, r. 9-905