If the Federal Unemployment Tax Act has been or shall be amended, interpreted, or extended so that employing units not heretofore included under the definition of "employer," as that term is used in this chapter, are included under such definition after said Act of Congress is so amended, interpreted, or extended, then, subject to other provisions of this chapter benefits shall become payable to any individual on the basis of wages earned in the employ of such newly defined employer, and such wages shall be available to any individual for determining his or her eligibility for benefits after the effective date of such extension, or after the date when such newly defined employer's approved election to be so defined shall have made him or her subject to this chapter, and the benefit year of such individual shall have begun subsequent to the date such newly defined employer became subject to this chapter.