45 C.F.R. § 1303.4
In accordance with section 640(b) of the Act, federal financial assistance to a grant recipient will not exceed 80 percent of the approved total program costs. A grant recipient must contribute 20 percent as non-federal match each budget period. The responsible HHS official may approve a waiver of all or a portion of the non-federal match requirement on the basis of the grant recipient's written application submitted for the budget period and any supporting evidence the responsible HHS official requires. In deciding whether to grant a waiver, the responsible HHS official will consider the circumstances specified at section 640(b) of the Act and whether the grant recipient has made a reasonable effort to comply with the non-federal match requirement.
45 C.F.R. §1303.4