D.C. Code § 9-421.11
The Mayor of the District of Columbia is directed to cancel all assessments for improvements completed within 3 years prior to February 20, 1931, levied under the authority of this subchapter, relating to assessments for the paving of streets, avenues, and roads, or under § 9-401.04, relating to assessments for laying curbs; and the Mayor is further directed to reassess the cost of such improvements against the abutting property in accordance with the provisions of this subchapter, which assessments shall become a lien upon the abutting property and be collected in the manner provided under this subchapter. Where assessments for such improvements have been paid in whole or in part the Mayor shall refund, within the limits of appropriations by Congress therefor, to the persons paying the same, the excess, if any, of such payments over the amounts of the reassessments levied under §§ 9-421.01 to 9-421.12.
D.C. Code § 9-421.11
Real property tax sales, refund of erroneously paid taxes, see § 47-1317. .