It's about to get a lot harder to buy a green card.

The U.S. government runs a program that grants permanent residency to foreigners who sink at least $500,000 into a job-creating investment. The controversial immigrant investor program, known as EB-5, has been hugely popular with rich Chinese, but lawmakers are considering changes that could make getting a green card a bit tougher.

Supporters of the program say foreign investors have provided an important alternative source of financing, benefiting major real estate investments, such as Brooklyn's Atlantic Yards and smaller projects, like a North Dakota factory that makes biodegradable food containers.

But critics argue that it's a way for the global elite to buy U.S. citizenship. They say the scheme has too much red tape and parts of it are mismanaged to the point of fraud.

A number of reform proposals have been floated in Congress, which recently issued a temporary stopgap measure that will keep the current program running past its original expiration date until early December.

Here are four ways the program is likely to change:

1) It's going to get more expensive

The EB-5 program currently requires foreign investors to invest at least $500,000 or $1 million depending on the project, and prove those funds helped to create jobs. One of the legislative proposals on the table now would raise those amounts to $800,000 to $1.2 million, while keeping the job-creation provisions.

The program, which has been around since 1990, is long overdue for an investment amount adjustment, though the higher rate is unlikely to "decrease the number of people investing in the program," said Marcum's David Appel, an accountant who works on EB-5 issues.