Whenever the processing tax first takes effect, there shall be levied, assessed, and collected a tax to be paid by such person equivalent to the amount of the processing tax which would be payable with respect to the commodity from which processed if the processing had occurred on such date. Such tax upon articles imported prior to, but in customs custody or control on, the effective date, shall be paid prior to release therefrom. In the case of sugar, the tax on floor stocks, except the retail stocks of persons engaged in retail trade, shall be paid for the month in which the stocks are sold, or used in the manufacture of other articles, under rules and regulations prescribed by the Commissioner of Internal Revenue with the approval of the Secretary of the Treasury.

Whenever the processing tax is wholly terminated, (A) there shall be refunded or credited in the case of a person holding such stocks with respect to which a tax under this chapter has been paid, or (B) there shall be credited or abated in the case of a person holding such stocks with respect to which a tax under this chapter is payable, where such person is the processor liable for the payment of such tax, or (C) there shall be refunded or credited (but not before the tax has been paid) in the case of a person holding such stocks with respect to which a tax under this chapter is payable, where such person is not the processor liable for the payment of such tax, a sum in an amount equivalent to the processing tax which would have been payable with respect to the commodity from which processed if the processing had occurred on such date: Provided, That in the case of any commodity with respect to which there was any increase, effective prior to June 1, 1934, in the rate of the processing tax, no such refund, credit, or abatement, shall be in an amount which exceeds the equivalent of the initial rate of the processing tax in effect with respect to such commodity.

Any sugar, imported prior to the effective date of a processing tax on sugar beets and sugarcane, with respect to which it is established (under regulations prescribed by the Commissioner of Internal Revenue, with the approval of the Secretary of the Treasury) that there was paid at the time of importation a duty at the rate in effect on January 1, 1934, and (2) any sugar held on April 25, 1934, by, or to be delivered under a bona fide contract of sale entered into prior to April 25, 1934, to, any manufacturer or converter, for use in the production of any article (except sugar) and not for ultimate consumption as sugar, and (3) any article (except sugar) processed wholly or in chief value from sugar beets, sugarcane, or any product thereof, shall be exempt from taxation under subsection (a) of this section, but sugar held in customs custody or control on April 25, 1934, shall not be exempt from taxation under subsection (a) of this section, unless the rate of duty paid upon the withdrawal thereof was the rate of duty in effect on January 1, 1934.

Whenever, on or after June 1, 1934, the rate of the processing tax on the processing of the commodity generally or for any designated use or uses, or as to any designated product or products thereof for any designated use or uses, or as to any class of products, is decreased, there shall be credited or refunded to such person an amount equivalent to the difference between the rate of the processing tax payable or paid at the time immediately preceding the decrease in rate and the rate of the processing tax which would have been payable with respect to the commodity from which processed, if the processing had occurred on such date: Provided, however, That no such credit or refund shall be made in the case of hogs unless the rate of the processing tax immediately preceding said decrease is equal to, or less than, the rate of the processing tax in effect on the date on which any floor stocks tax was paid prior to the adoption of this subsection. In the case of wheat the provisions of this paragraph and of paragraph (2) of this subsection shall apply to flour, prepared flour and cereal preparations made chiefly from wheat, as classified in Wheat Regulations, Series 1, Supplement 1 only; in the case of sugarcane and sugar beets the provisions of this paragraph and of paragraph (2) of this subsection shall apply to sugar only.

Whenever the rate of the processing tax on the processing of the commodity generally, or for any designated use or uses, or as to any designated product or products thereof for any designated use or uses, or as to any class of products, is increased, there shall be levied, assessed and collected a tax to be paid by such person equivalent to the difference between the rate of the processing tax payable or paid at the time immediately preceding the increase in rate and the rate of the processing tax which would be payable with respect to the commodity from which processed, if the processing had occurred on such date.

Whenever the processing tax is suspended or is to be refunded pursuant to a certification of the Secretary of Agriculture to the Secretary of the Treasury, under section 615(a) of this title, the provisions of paragraph (1) of this subsection shall become applicable.

Whenever the Secretary of Agriculture revokes any certification to the Secretary of the Treasury under section 615(a) of this title, the provisions of paragraph (2) of this subsection shall become applicable.

The provisions of this subsection shall be effective on and after June 1, 1934.