If you're growing old and depending on Medicare, you have someone to thank for keeping the system afloat: Immigrants, including those who entered the country illegally.
A study published in the medical journal Health Affairs on Wednesday found that immigrants generated a $13.8 billion surplus in the Medicare system in 2009. That's means they put a lot more into the system than they took out.
Meanwhile, people born in the U.S. accounted for a $30.9 billion deficit.
The biggest reason immigrants are able to contribute more than their share is because they're more likely to be of working age and part of the labor force. Of all immigrants in the U.S., 80 percent are between the ages of 18-64, versus 59 percent of the U.S.-born population, according to 2010 census data.
You generally have to be 65 years of age or older to receive Medicaid. There are a lot more native-born people than immigrants eligible for the federal healthcare program, so that means immigrants are less likely to be a drain.
Non-citizens specifically play an outsized role in paying our national Medicare bills.
Legal immigrants contribute to the system through payroll taxes, using valid Social Security numbers.
But undocumented immigrants also add to the coffers, some using other people's socials. Since undocumented immigrants can't receive Medicare, they could be paying for a service they'll never use.
Even when immigrants do use Medicare, they tend to use fewer services than people born in the U.S., according to the report.
All of this is a pretty big deal. Medicare makes up a fifth of all annual healthcare expenditures in the U.S., and politicians are constantly warning that system might fail as our population continues to grow older.
An immigration reform bill that's heading to the Senate floor in early June would create a pathway to citizenship for undocumented immigrants. If a bill like that passes, millions of people could become eligible to use Medicare who were previously barred.
Still, immigrants would probably continue to underwrite the Medicare system, the report found. Since immigrants tend to be younger, if the country keeps bringing in immigrant workers, they'll likely keep adding more to that system.
This article was updated at 2:50 p.m.