A brokerage house notification that the customer's equity in a margin account has fallen below the maintenance requirement level. If the client fails to immediately deliver the required margin by depositing more funds or securities into the account, his or her position will be liquidated. Also known as a "margin call". Taobiz explains House Call House call limits are usually higher than the limits mandated by the National Association of Securities Dealers (NASD), a self-regulatory group, and the major exchanges with jurisdiction over these rules. For example, if a brokerage set its house call limits equal to the limits mandated by NASD, the brokerage would violate this mandate each time a client required additional margin. Thus, the house limit provides the brokerage with a cushion and is in addition to the initial margin requirements set by Regulation T of the Federal Reserve Board.