D.C. Code § 26-106

Each such savings bank, savings company, banking institution, and trust company shall, before the declaration of a dividend on its shares of common stock, carry not less than one-tenth part of its net profits of the preceding half year to its surplus fund until the same shall equal the amount of its common stock; provided, that for the purposes of this section, any amounts paid into a fund for the retirement of any preferred stock or debentures of any such savings bank, savings company, banking institution, or trust company, out of its net earnings for such half-year period shall be deemed to be an addition to its surplus if, upon the retirement of such preferred stock or debentures, the amount so paid into such retirement fund for such period may then properly be carried to surplus. In any such case the savings bank, savings company, banking institution, or trust company shall be obligated to transfer to surplus the amount so paid into such retirement fund for such period, on account of the preferred stock or debentures as such stock or debentures are retired.