D.C. Code § 9-421.06
No assessments shall be levied for repaving where the original pavement was laid at the whole cost of the owner or owners of the abutting property if the said original pavement was constructed under a permit issued by the District of Columbia and under the supervision and direction of an authorized engineer and inspector of the Department of Transportation of said District, in strict accordance with the then current specifications and design for pavements of the type for which permit was issued; provided, that where curb, or curb and gutter, or a part of the roadway has or have been paved under proper permit, subject to engineering and inspection as above stated, the assessment for paving other parts of the roadway, placing curb, or curb and gutter, when the same is done at public expense, shall be made against property abutting on the highway as provided in this subchapter, credit being given in such assessment for the half cost of the pavement laid by the owner under permit as above, estimated on the basis of the contract rates for such work at the date of the performance of the assessable work, so that the total cost to the owner for such improvements shall not exceed the amount of assessments which would have been made under this subchapter, had the improvements been all made at public expense.
D.C. Code § 9-421.06