Except as otherwise provided, the value of an investment (including a payment or receipt on the investment) on a date must be determined using one of the following valuation methods consistently for all purposes of section 148 to that investment on that date:
(i) Plain par investment --
OUTSTANDING PRINCIPAL AMOUNT. A plain par investment may be valued at its outstanding stated principal amount, plus any accrued unpaid interest on that date.
(ii) Fixed rate investment --
PRESENT VALUE. A fixed rate investment may be valued at its present value on that date.
(iii) Any investment --
FAIR MARKET VALUE. An investment may be valued at its fair market value on that date.