12 CFR §5.63

1. (a)General limitation. Except as provided by 12 U.S.C. 59 and § 5.46, a national bank may not withdraw, or permit to be withdrawn, either in the form of a dividend or otherwise, any portion of its permanent capital. Further, a national bank may not declare a dividend in excess of undivided profits.
2. (b)Preferred stock. The provisions of 12 U.S.C. 56 do not apply to dividends on preferred stock. However, if the undivided profits of the national bank are not sufficient to cover a proposed dividend on preferred stock, the proposed dividend constitutes a reduction in capital subject to 12 U.S.C. 59 and § 5.46.