(a) Under the Acts of May 16, 1930 (46 Stat. 367; 43 U.S.C. 424 through 424e) and March 31, 1950 (64 Stat. 39; 43 U.S.C. Sup., 375b through 375f) lands may be sold either for cash or upon deferred payments. A sale providing for deferred payments shall be upon terms to be established by the Commissioner, except that the Commissioner shall require the annual payment of interest at six percent per annum on the unpaid balance.

(b) Under the Act of May 20, 1920 (41 Stat. 605; 43 U.S.C. 375) lands may be sold either for cash or upon deferred payments. In connection with a sale providing for deferred payments the Commissioner shall require that not less than one-fifth the purchase price in cash be paid at the time of sale and that the remainder be payable in not more than four annual payments with interest at six percent per annum on the unpaid balance.

(c) All payments shall be made to the official of the Bureau of Reclamation specified in the contract of sale.