D.C. Code § 47-2503

Private banks or bankers not incorporated shall pay a tax of $500 per annum. Every person, firm, company, or association not incorporated having a place of business where credits are opened by the deposit or collection of moneys or currency subject to be paid or remitted upon draft, check, or order, or where money is advanced or loaned on stocks, bonds, bullion, bills of exchange, or promissory notes, or where stocks, bonds, bills of exchange, or promissory notes are received for discount or for sale, shall be regarded as a private bank or banker.