each heading in this title, except for Federal Emergency Management Agency—Disaster Relief Fund , shall only be used for the purposes specifically described under that heading. 10602. (a) Assistance provided under the emergency declaration issued by the President on March 13, 2020, pursuant to section 501(b) of the Robert T. Stafford Disaster Relief and Emergency Assistance Act ( 42 U.S.C. 5121–5207 ), and under any subsequent major declaration under section 401 of such Act that supersedes such emergency declaration, shall be at a 100 percent Federal cost share. (b) Amounts repurposed under this section that were previously designated by the Congress, respectively, as an emergency requirement or as being for disaster relief pursuant to the Balanced Budget and Emergency Deficit Control Act are designated by the Congress as being for an emergency requirement pursuant to section 251(b)(2)(A)(i) of the Balanced Budget and Emergency Deficit Control Act of 1985 or as being for disaster relief pursuant to section 251(b)(2)(D) of the Balanced Budget and Emergency Deficit Control Act of 1985. 10603. Notwithstanding any other provision of law, any amounts appropriated for Department of Homeland Security—Federal Emergency Management Agency—Disaster Relief Fund in this Act are available only for the purposes for which they were appropriated. 10604. (a) For calendar year 2020 and calendar year 2021, any provision of law limiting the aggregate amount of premium pay or overtime payable on a biweekly or calendar year basis, or establishing an aggregate limitation on pay, shall not apply to any premium pay or overtime that is funded, either directly or through reimbursement, by the Federal Emergency Management Agency—Disaster Relief Fund related to an emergency or major disaster declared in calendar year 2020. (b) Pay exempted from otherwise applicable limits under this section shall not cause the aggregate pay for the calendar year to exceed the rate of basic pay payable for a position at level II of the Executive Schedule