(a) In general. If the statement is filed in accordance with §1.9000-3 and if that portion of the increase in tax which is due before December 15, 1955 (without regard to any extension of time for payment and without regard to the provisions of §§1.9000-2 to 1.9000-8, inclusive), is paid in full on or before such date, then no interest shall be due with respect to that amount. The provisions of this paragraph may be illustrated by the following example:

Interest shall be computed under the applicable provisions of the internal revenue laws on any portion of the increase in tax shown on the statement which is due after December 15, 1955, and which is not paid when due.

(b) Limitation on application of waiver. The provisions of paragraph (a) of this section shall not apply to any portion of the increase in tax shown on the statement if such increase reflects an amount in excess of that attributable solely to the repeal of sections 452 and 462, i. e., is attributable in whole or in part to excessive or unwarranted deferrals or accruals under section 452 or 462, as the case may be, in computing the tax liability with the application of such sections. Notwithstanding the preceding sentence, paragraph (a) of this section shall be applicable if the taxpayer can show that the tax liability as computed with the application of sections 452 and 462 is based upon a reasonable interpretation and application of such sections as they existed prior to repeal. If the taxpayer complied with the provisions of the regulations under sections 452 and 462 in computing the tax liability with the application of such sections, he will be regarded as having reasonably interpreted and applied sections 452 and 462. In this regard, it is not essential that the taxpayer submit with his return the detailed information required by such regulations in support of the deduction claimed under section 462, but such information shall be supplied at the request of the Commissioner.

(c) Interest for periods prior to June 16, 1955. No interest shall be imposed with respect to any increase in tax resulting solely from the repeal of sections 452 and 462 for any period prior to June 16, 1955 (the day after the date of the enactment of the Act of June 15, 1955). The preceding sentence does not apply to that part of any increase in tax which is due to the improper application of sections 452 and 462. The provisions of this paragraph shall not apply to interest imposed under section 3779 of the Internal Revenue Code of 1939. (See paragraph (d) of this section.)

(d) Amounts deferred by corporations expecting carrybacks. Interest shall be imposed at the rate of 6 percent on so much of the amount of tax deferred under section 3779 of the Internal Revenue Code of 1939 as is not satisfied within the meaning of section 3779(i)(1), notwithstanding the fact that a greater amount would have been satisfied, had sections 452 and 462 not been repealed. Interest will be imposed at such rate until the amount not so satisfied is paid.