District of Columbia Code Division VIII. General Laws. § 47-4202. Interest on overpayments.

(1) In the case of a refund, from the date of the overpayment to a date (to be determined by the Mayor) preceding the date of the refund check by not more than 60 days, whether or not the refund check is accepted by the taxpayer after tender of the check to the taxpayer. The acceptance of the check shall be without prejudice to any right of the taxpayer to contest the amount of the overpayment and interest thereon.

(2) In the case of a return filed on or before the last day prescribed for filing the return (determined with regard to extension), interest shall not be allowed or paid before:

(3) In the case of a return filed after the last date prescribed for filing the return (determined with regard to extension), an amended return, or a claim for refund or credit, interest shall not be allowed or paid before:

(4) If an adjustment initiated by the Mayor results in a refund of an overpayment, interest on the overpayment shall be computed from:

(c)(1) For overpayments on which interest is due on or before December 31, 2012, the overpayment rate shall be 6% per year simple interest.

(2) For overpayments on which interest is due beginning January 1, 2013, the overpayment rate for each annual period shall be one percentage point above the primary credit discount rate for the Richmond Federal Reserve Bank as of the previous September 30, rounded to the nearest whole number, but not exceeding 6% in the aggregate.