June 5 (UPI) — The Treasury Department on Friday issued an advisory that financial institutions, including banks and casinos, to “be vigilant” against signs of unlawful employment of illegal immigrants.

The Department’s Financial Crimes Enforcement Network, called FinCEN, in the advisory calls on the institutions employ methods to detect schemes covering up the employment of people who are not authorized to work in the United States.

Treasury Secretary Scott Bessent said in a FinCEN press release that part of the Trump administration’s crackdown on illegal immigration includes “securing our financial system.”

“This administration will not allow illegal aliens to abuse financial institutions to steal billions of dollars from hardworking American taxpayers,” Bessent said.

In order for non-immigrants to work in the United States, employers are required to petition with U.S. Citizenship and Immigration Services for eligibility, before a prospective employee either applies to the State Department for a visa or enters the country through a port of entry, according to USCIS.

FinCEN said in the release that the hiring, concealing and exploiting of workers without visas can give employers advantages over other businesses, depress wages, facilitate identity theft and steal tax revenue from the United States.

The agencies additionally said that the hiring of these workers can also help fund and assist criminal enterprises that include drug trafficking and human trafficking.

The financial institutions are being asked to watch out for red flags of shell companies, identity theft, fraudulently used social security and worker identification numbers, shell companies and a raft of other detectable signs of fraud.

In addition to depository institutions such as banks, credit unions, money services businesses and securities and futures firms, FinCEN has aimed the advisory at casinos, the insurance industry, mortgage companies and brokers, and the precious metals and jewelry industries.

The Treasury Department said that more than $2.5 billion in suspicious activity reported by financial institutions was linked to payroll fraud schemes in 2025 alone, noting one multi-year scheme that cost the United States more than $38 million in tax revenue.