Updated

The U.S. Postal Service (USPS) and federal websites that allow Americans to request free COVID-19 tests have begun accepting orders. 

COVIDTests.gov officially launched Wednesday, after a beta testing phase on Tuesday.

However, the pilot testing revealed glitches, according to social media users, including for residents of apartment buildings and people who receive their mail at post office boxes.

An order is limited to four tests per residential address – applied to the first 500 million tests – at no cost, including no shipping fee.

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"The tests will be completely free—there are no shipping costs and you don’t need to enter a credit card number," the government website says. 

The USPS site says orders will ship starting in late January.

Tests will "typically ship within 7-12 days of ordering" through the U.S. Postal Service, which reports shipping times of one to three days for its first-class package service in the continental U.S.

While the White House said that it would double its order for at-home tests to distribute around the country to 1 billion tests, the Biden administration has faced criticism for the low inventory of at-home rapid antigen tests available and long lines for PCR testing.

Youngstown City Health Department worker Faith Terreri grabs two at-home COVID-19 test kits to be handed out during a distribution event, Dec. 30, 2021, in Youngstown, Ohio.

Youngstown City Health Department worker Faith Terreri grabs two at-home COVID-19 test kits to be handed out during a distribution event, Dec. 30, 2021, in Youngstown, Ohio.  (AP Photo/David Dermer, File)

The cost of purchasing and distributing the first 500 million tests is estimated to be $4 billion.

Starting Saturday, private insurance companies were required to cover the cost of at-home, rapid tests, allowing Americans to be reimbursed for tests purchased online and at pharmacies – covering up to eight tests per month.

While insurance plans that work with pharmacies and retailers will be required to reimburse up to $12 per test if purchased through an out-of-network retailer, plans that don't move proactively to set up a network of pharmacies would have to cover the full retail price that the customer paid.

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Original Medicare does not pay for over-the-counter COVID-19 tests but some Medicare Advantage Plans do. People with Original Medicare can pick up free at-home tests from health centers and Medicare-certified clinics.

People with Original Medicare also pay nothing for a test when getting it from a laboratory, pharmacy, doctor or hospital and when it's ordered by a doctor or health care worker and can get up to one lab-performed test a year without an order, at no cost.

In accordance with the American Rescue Plan, state Medicaid and Children's Health Insurance Program (CHIP) are required to cover Food and Drug Administration-authorized at-home tests. 

The HHS website has resources for people who are uninsured to find testing and COVID-19 care.

The administration said it would also launch a call line to aid those unable to access the website and work with national and local community-based organizations to reach the nation's "hardest-hit and highest-risk communities."

In addition, the White House wrote it had "rapidly stood up many new, federal free testing sites across the nation over the past several weeks."

The Centers for Disease Control and Prevention (CDC) recommends that Americans use at-home tests if they begin to have symptoms, at least five days after coming in close contact with someone who has COVID-19 or are gathering indoors with a group of people who are at risk of severe disease or unvaccinated.

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There are nine at-home, rapid tests on the market.

The Associated Press contributed to this report.