(1) Issue price. If a substantial amount of the debt instruments in an issue is issued for money, the issue price of each debt instrument in the issue is the first price at which a substantial amount of the debt instruments is sold for money. Thus, if an issue consists of a single debt instrument that is issued for money, the issue price of the debt instrument is the amount paid for the instrument. For example, in the case of a debt instrument evidencing a loan to a natural person, the issue price of the instrument is the amount loaned. See 1.1275-2(d) for rules regarding Treasury securities. For purposes of this paragraph (a), money includes functional currency and, in certain circumstances, nonfunctional currency. See 1.988-2(b)(2) for circumstances when nonfunctional currency is treated as money rather than as property.