Real Time Transparency Act of 2021 This bill revises the notification requirement for campaign contributions of $1,000 or more. Specifically, the bill applies this requirement to (1) any political committee, not just a candidate's principal campaign committee; and (2) cumulative contributions of $1,000 or more during a calendar year, instead of only single contributions that are received by a committee less than 20 days but more than 48 hours before the day of an election. Only the Federal Election Commission (FEC) must be notified within 48 hours of receiving these contributions, instead of the FEC and others. Any amount transferred by a joint fundraising committee established by a candidate's authorized committee to any other authorized committee of that candidate shall be treated as a contribution.