No one should mail their ballots after Oct. 27, the Postal Service’s recommended date to ensure they arrive on time.

The United States Postal Service (USPS) recommends voters mail their absentee ballots by Tuesday, Oct. 27, to make sure they arrive at their local county board of elections on time. 

According to the USPS, all domestic, non-military voters should mail their completed ballots at least one week prior to their state’s deadline—or, in many places, Election Day. Because of an increase in mail-in voting across the country, it’s best to send your ballot as soon as you can. 

USPS aims to deliver mail within one to three days for First Class letters. Assuming the agency is able to maintain that benchmark, a ballot mailed on Oct. 27 would arrive at its destination on Oct. 30, which allows an additional four days for the ballot to be verified and counted. If a ballot takes five days to reach the appropriate location, instead of three, it would still have two days to be counted. 

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NBC-owned TV stations across the country participated in an unscientific, yet still illuminating, test of the Postal Service’s delivery times. The stations sent First Class letters to each other to see if the agency was effectively meeting its benchmark. They found that about 88% of letters reached their intended destination within the three-day window, and 98% of letters made it in five. 

If the test results hold for the country as a whole, this means that mailing your ballot by Oct. 27 has a 98% chance of being delivered on or before Election Day.

The US Supreme Court has already signaled how vital it is that you either mail your ballot as early as possible, or forego the mail altogether and simply drop off your ballot in person. On Monday, the Court ruled against an order in Wisconsin that allowed mail-in ballots received up to six days after the Nov. 3 election to be counted. That means the roughly 360,000 absentee ballots that have yet to be returned need to be received by Election Day to be counted.

Democrats in the state—as they’ve done elsewhere—have argued that the flood of absentee ballots and other challenges posed by the coronavirus pandemic makes it necessary to extend the period in which ballots can be counted. Wisconsin is one of the nation’s hot spots for COVID-19, with hospitals treating a record high number of patients with the disease.

During the state’s primary in April, roughly 80,000 ballots were received late. Those ballots were counted, however, due to the state’s extension for primary voting.

“On the scales of both constitutional justice and electoral accuracy, protecting the right to vote in a health crisis outweighs conforming to a deadline created in safer days,” Justice Elena Kagan wrote in her dissent.

According to the US Election Project, more than 44 million Americans have voted by mail this year. That figure is a significant increase over the 2018 midterm election, when 31 million people voted by mail. 

In total, more than 66 million people have already cast their ballots as of Tuesday morning. 

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Those figures appear to show that Americans across the country have largely been unswayed by President Donald Trump’s fear-mongering over the security of mail-in voting. He has claimed, without evidence, that widespread mail-in voting would lead to fraud. 

“Big problems and discrepancies with Mail In Ballots all over the USA,” Trump said in a tweet Monday evening, without providing anything context.

Experts agree that sending ballots via mail is safe. There are processes in place to prevent issues like double voting and ensuring ballots are submitted only by people who are legally allowed to vote. 

In fact, FBI Director Christopher Wray—a Trump nominee—told Congress that there is no evidence of widespread voter fraud. “[We] have not seen, historically, any kind of coordinated national voter fraud effort in a major election, whether it’s by mail or otherwise,” he testified in September. 

Lawmakers have also cited concerns in recent months that a sudden shift toward mail-in voting could favor one political party over another. This claim is also unfounded: Studies show that there is no evidence that vote-by-mail favors one party over another. Instead, states that have expanded their use of mail-in ballots have seen a modest, but equal, increase in voter turnout among both parties. 

Remember: If you want to ensure your ballot is counted, it’s imperative you act right now.

Additional reporting by the Associated Press.

READ MORE: Timing Is Everything: A Guide to Voting Early When You Think the Lines Will Be Long