TITLE IV—SUNSET OF SALES TAX IF SIXTEENTH AMENDMENT NOT REPEALED
SEC. 401. ELIMINATION OF SALES TAX IF SIXTEENTH AMENDMENT NOT REPEALED.
If the Sixteenth Amendment to the Constitution of the United States is not repealed before the end of the 7-year period beginning on the date of the enactment of this Act, then all provisions of, and amendments made by, this Act shall not apply to any use or consumption in any year beginning after December 31 of the calendar year in which or with which such period ends, except that the Sales Tax Bureau of the Department of the Treasury shall not be terminated until 6 months after such December 31.
http://thomas.loc.gov/cgi-bin/query/C?c113:./temp/~c113GoGY7A
The Federal Income Tax is completely scrapped (see also Section 202):
TITLE I—REPEAL OF THE INCOME TAX, PAYROLL TAXES, AND ESTATE AND GIFT TAXES
Sec. 101. Income taxes repealed.
Sec. 102. Payroll taxes repealed.
Sec. 103. Estate and gift taxes repealed.
And a liberal congress could just amend that section and leave both in place.