D.C. Code § 41-113

All employee benefit trust distributions and any income or other increment thereon is presumed abandoned if the owner within 3 years after it becomes payable or distributable has not accepted the distribution, corresponded in writing concerning the distribution, or otherwise indicated an interest as evidenced by a memorandum or other record on file with the fiduciary of the trust or custodial fund or administrator of the plan under which the trust or fund is established.