Even if your COVID-19 tests' expiration dates have passed, the tests may still work.

Tests' expiration dates

According to FDA, expiration dates on COVID-19 tests refer to "how long the test should work as expected and is measured from the date the test was manufactured."

However, the agency has extended the expiration dates for 37 approved home COVID-19 tests that are mostly antigen tests, which detect a viral protein on the surface of the coronavirus. FDA extended these expiration dates because manufacturers showed new data proving the tests can provide accurate results beyond their original expiration date.

"It's important for people to understand that the reason those expirations existed in the first place is we didn't have information, just based on the rapid development of testing, on how long the pieces of test were good for," said Rachael Piltch-Loeb, a research scientist at Harvard University's T.H. Chan School of Public Health. "It's important to check into whether or not the expiration has been updated."

FDA has a test expiration date database where consumers can check tests by manufacturer and test name to see if their expiration date has been extended.

Can you still use an expired COVID-19 test?

If your COVID-19 test is beyond its extended expiration date, FDA advises against using it, as expired tests could "degrade, or break down, over time," leading to "inaccurate or invalid test results."

Omai Garner, director of clinical microbiology at UCLA Health System, said he recommends you get new at-home tests if the only tests you have are expired. If you have to use an expired test, try to use one that's only recently expired.

"If it's a year expired, go get more tests," Garner said. "If the expiration date was yesterday, it's probably still going to work."

The federal government is once again offering free COVID-19 tests by mail for those who need them. Experts say they expect the COVID-19 tests will be able to detect newer variants of the virus that are currently circulating, like BA.2.86, EG.5, and FL.1.5.1. (Alltucker, USA Today, 9/29; Miranda, Axios, 9/26; Otis/Calfas, Wall Street Journal, 9/20; Constantino, CNBC, 9/5)