; and (B) for fiscal year 2020 and each fiscal year thereafter, if the unobligated amount remaining in the Fund on the first day of the applicable fiscal year is less than $2,000,000,000, the amount equal to the difference between $2,000,000,000 and the unobligated amount remaining in the Fund on the first day of such fiscal year. (2) Emergency designation (A) Statutory PAYGO This subsection is designated as an emergency requirement pursuant to section 4(g) of the Statutory Pay-As-You-Go Act of 2010 ( 2 U.S.C. 933(g) ). (B) Senate designation In the Senate, this subsection is designated as an emergency requirement pursuant to section 4112(a) of H. Con. Res. 71 (115th Congress), the concurrent resolution on the budget for fiscal year 2018. (3) Limitation Amounts appropriated under this Act shall supplement, and not supplant other Federal, State, and local governmental amounts provided for public health response activities, including amounts provided through any emergency supplemental appropriations Act. (f) GAO reports Not later than 1 year after the date of enactment of this Act and annually thereafter for 4 years, the Comptroller General of the United States shall submit a report to Congress on the Federal response to infectious disease outbreaks during the reporting period, best practices for emergency public health response and interagency coordination, the use of funding sources in public health emergency response, and the use of the Fund established by this Act.