Under the 1996 welfare reform law signed by President Clinton, persons not legally present in the United States in contravention of U.S. immigration laws are not eligible to receive refundable federal tax credits such as the Child Tax Credit (CTC) or the Additional Child Tax Credit (ACTC). These tax credits provide a federal benefit payment to persons whose total income tax liability is less than the value of the credit - effectively a form of income subsidy for persons having no income tax liability. Changes to refundable tax credits made in the failed 2009 Stimulus law eliminated the ability of the Internal Revenue Service to enforce the ban on illegal aliens claiming these payments. An audit by the Department of the Treasury's Inspector General for Tax Administration has determined that more than $4.2 billion in payments were made under the credits to illegal aliens in 2010. Clarifying the ability of the IRS to enforce the prohibition from the 1996 welfare reform law will save at least $4 billion annually if the credits are extended beyond 2012, and will reduce the incentive for persons to violate U.S. immigration laws in pursuit of federal payments to which they are not legally entitled.