Section 212 of the Immigration and Nationality Act requires that legal immigrants demonstrate that they won't be a public charge before they're granted entry into the United States. However, according to Sen. Jeff Sessions (R-Ala.) the bill being drafted by the Gang of Eight that will offer instant legal status and work permits to the 11-19 million illegal aliens living in the country won't subject amnestied illegal aliens to the public charge rule, which could cost taxpayers trillions of dollars.
Most welfare programs require the recipient to be a green card holder or a U.S. citizen, so illegal aliens that receive an amnesty won't be eiligible for certain programs. But they will be eligibile for Social Security if they've legally worked the required 40 quarters to receive the benefit and they'll be eligibile for beneifts under the Affordable Care Act.
Once they receive a green card, however, which the Gang of Eight's proposal will grant after a certain period of time, illegal aliens would become eligible to receive all forms of welfare. According to a statement released by Sen. Sessions office earlier this week, "once this status ends and they become eligible for green cards, those who illegally immigrated will have access to a wide array of public assistance programs. Green card holders are currently eligible for Medicaid, TANF, Supplemental Security Income, child care assistance, food stamps, and a variety of other welfare benefits and public aid programs. The Budget Committee Republican staff estimates that costs could be upwards of $40 billion in 2022 alone, just for Medicaid and Obamacare."
Currently, the Obama Administration does not adhere to the public charge requirement in Section 212 of the INA, so it's likely that illegal aliens that receive an amnesty will not be subject to the requirement when they become eligible for a green card. According to Sen. Sessions, "To be effective, any immigration reform must therefore ensure that a reliable public charge standard is being applied for all immigrants, legal and illegal, and that any incentive to immigrate illegally in order to receive public benefits is removed."
For more information, see the Senate Budget Committee's release.