Every association may set up and maintain the reserves authorized by this subchapter. On the semiannual closing dates after the payment of or provision for all expenses, each association shall, before the declaration of a dividend for the semiannual period, transfer to a separate reserve account, which shall be set up and maintained for the sole purpose of absorbing losses, an amount equal to 5 percent of its net earnings, until such reserve equals 10 percent of its capital, such account being in the nature of a guaranty fund. If and whenever the guaranty fund is not equal to 10 percent of its capital, semiannual credits as above provided shall again be made to the guaranty fund until it shall again be made equal to 10 percent of its capital. The board of directors may make additional transfers to other reserve accounts. In no event shall dividends be declared and be paid out of capital.