(i) In general.
The investment of amounts that are part of a reasonably required reserve or replacement fund in higher yielding investments will not cause an issue to consist of arbitrage bonds. A reasonably required reserve or replacement fund may consist of all or a portion of one or more funds, however labelled, derived from one or more sources. Amounts in a reserve or replacement fund in excess of the amount that is reasonably required are not part of a reasonably required reserve or replacement fund.
(ii) Size limitation.
The amount of gross proceeds of an issue that qualifies as a reasonably required reserve or replacement fund may not exceed an amount equal to the least of 10 percent of the stated principal amount of the issue, the maximum annual principal and interest requirements on the issue, or 125 percent of the average annual principal and interest requirements on the issue. If an issue has more than a de minimis amount of original issue discount or premium, the issue price of the issue (net of pre-issuance accrued interest) is used to measure the 10 percent limitation in lieu of its stated principal amount. For a reserve or replacement fund that secures more than one issue (e.g. a parity reserve fund), the size limitation may be measured on an aggregate basis.
(iii) Valuation of investments.
Investments in a reasonably required reserve or replacement fund may be valued in any reasonable, consistently applied manner that is permitted under section 1.148-5.
(iv) 150 percent debt service limitation on investment in nonpurpose investments for certain private activity bonds.
Section 148(d)(3) contains additional limits on the amount of gross proceeds of an issue of private activity bonds, other than qualified 501(c)(3) bonds, that may be invested in higher yielding nonpurpose investments without causing the bonds to be arbitrage bonds. For purposes of these rules, initial temporary period means the temporary periods under paragraphs (e)(2), (e)(3), and (e)(4) of this section and under section 1.148-9(d)(2)(i), (ii), and (iii).