17 CFR § 41.47 - Withdrawal of margin.
(a) By the customer. Except as otherwise provided in § 41.46(e)(1)(ii) of this subpart, cash, securities, or other assets deposited as margin for positions in an account may be withdrawn, provided that the equity in the account after such withdrawal is sufficient to satisfy the required margin for the security futures and related positions in the account under this Regulation (Subpart E, §§ 41.42 through 41.49).
(b) By the security futures intermediary. Notwithstanding paragraph (a) of this section, the security futures intermediary, in its usual practice, may deduct the following items from an account in which security futures or related positions are held if they are considered in computing the balance of such account:
(1) Variation settlement payable, directly or indirectly, to a clearing agency that is registered under section 17A of the Exchange Act or a derivatives clearing organization that is registered under section 5b of the Act;
(2) Interest charged on credit maintained in the account;
(3) Communication or shipping charges with respect to transactions in the account;
(4) Payment of commissions, brokerage, taxes, storage and other charges lawfully accruing in connection with the positions and transactions in the account;
(5) Any service charges that the security futures intermediary may impose; or
(6) Any other withdrawals that are permitted from a securities margin account under Regulation T, to the extent permitted under applicable margin rules.