US President Donald Trump’s administration is to make it more difficult for poorer legal migrants to extend their visas or gain permanent resident status (a green card).
The rule targets migrants who rely on public assistance, such as food aid or public housing, for more than a year.
Their applications will be rejected if the government decides they are likely to rely on public assistance in future.
The rule change would reinforce “ideals of self-sufficiency,” officials said.
Immigrants who already hold a green card are unlikely to be affected.
The new regulation, known as a “public charge” rule, was published in the Federal Register on Monday and will take effect on 15 October.
Applicants who do not meet income standards or who are likely to rely on benefits such as Medicaid (government-run health care) in future will be blocked from entering the country.
Those already in the US would not be able to obtain green cards or US citizenship.