Facebook has begun labelling posts from US President Donald Trump about voting, including one that claimed current rules on postal votes could lead to a "corrupt" election.
The Republican's posts now carry a link to official voting information.
The social network has also labelled several posts from Democratic presidential hopeful Joe Biden.
It follows a promise to begin labelling all posts about voting in the 2020 election, from any politician.
This policy was implemented in June, following criticism that the social network was not doing enough to tackle misinformation.
Founder Mark Zuckerberg said Facebook would begin to label posts that mentioned voting, but said it was not going to be an easy job.
"If someone says on election day that a city has been identified as a Covid hotspot, is that vote suppression or simply sharing health information?" he wrote in a blog.
"Because of the difficulty of judging this at scale, we are adopting a policy of attaching a link to our Voting Information Centre for posts that discuss voting, including from politicians. This isn't a judgement of whether the posts themselves are accurate, but we want people to have access to authoritative information either way.
At the time it was described by some as a compromise, because the blanket labelling would not allow people to distinguish legitimate posts about the election from misinformation.
Twitter began labelling some of the president's tweets in May, starting with one which referenced the Black Lives Matter protests, which was judged to glorify violence.
Some Facebook staff said at the time that they were ashamed that it did not remove or flag the same controversial post on its platform.
The Twitter labelling led to Mr Trump signing an executive order seeking to curb the longstanding legal protections of social media firms.
Mr Trump has also been vocal on social media about what he sees as the dangers of postal voting, known in the US as mail-out voting. He has repeatedly said that he does not trust it, but offers little evidence as to why he thinks it could lead to fraud.
Election experts have denied that this is the case. Postal voting could play a significant role in the 2020 election because of the coronavirus pandemic.
By Marianna Spring, specialist disinformation reporter
Facebook now looks to be following the blueprint set in May by Twitter in May, which first labelled Donald Trump's tweet when he criticised mail-out voting.
This does not come as a surprise, since the social media platform has been under increasing pressure from advertisers and campaign groups to do more to address misinformation on its site, especially from the US president in the build-up to the US election.
The approaches of the two social media platforms favoured by the US president still differ, though - as Facebook has pledged to label anything about voting in the US election that's shared, including by politicians, regardless of whether it's misleading.
This is a significant move from Facebook, which has previously seemed reluctant to tackle content shared by President Trump, and there is much speculation over why that is.
Nonetheless there are still big questions over Facebook's decision not to label other misleading claims made by President Trump about coronavirus, which Twitter has similarly refrained from flagging.