Be it enacted by the Senate and House of Representatives of the Philippines in Congress assembled:

SECTION 1. Section fifteen of Republic Act Numbered Fifty-six is hereby amended to read as follows:

"SEC. 15. Whenever any of the oils mentioned in section one hundred and forty-two of Commonwealth Act Numbered Four hundred and sixty-six are, during the period of five years from the effective date of this Act, used in aviation, fifty per centum of the specific tax paid thereon shall be refunded by the Collector of Internal Revenue upon the submission of a sworn certificate satisfactory to him proving that the said oils were actually used in aviation. No such refund shall be granted in respect to the oils used in aviation by citizens and corporations of foreign countries which do not grant equivalent refunds or exemptions in respect to similar oils used in aviation by citizens and corporations of the Philippines."

SEC. 2. This Act shall take effect upon its approval.

Approved, August 31, 1950.