Twitter community adds a context note to Joe Biden tweet:  President Joe Biden's official Twitter account tweeted, “The average billionaire in America pays 8% in federal taxes. Teachers and firefighters pay more than that. That’s why I proposed a minimum tax for billionaires. Republicans are against it, but I’m going to keep fighting for it.”  Twitter added a label to the post that read "Readers added context they thought people might want to know.” The added context read "This 8% claim has been repeatedly debunked as it comes from a theoretical calculation that included unrealized capital gains as taxable income even though current tax law does not." The context note also included links to PolitiFact, CNN and FactCheck.org articles to support the note. The label is part of Twitter’s Community Notes system. Twitter users are able to sign up as contributors to add context to tweets.