[1] Due to the COVID-19 pandemic in the United Kingdom, this season featured a truncated timeframe of just 16 weeks with a later start and fewer rounds.

Yorkshire Carnegie, later renamed Leeds Tykes, were relegated to National League 1 after finishing bottom of the 2019–20 RFU Championship.

[4] They were replaced in the RFU Championship by Saracens, who were relegated after finishing bottom of the 2019–20 Premiership Rugby table.

[8] On 2 February 2021, Ampthill announced that due to funding cuts and the costs associated with the COVID-19 pandemic, they might not be able to take part in the season.

Ahead of the season, Ealing, Doncaster and Saracens participated in the Trailfinders Challenge Cup, as a pre-season warm-up.

The top ranked team at the end of the league season chose which leg they play at home.

In June 2021, it was confirmed that only Saracens were eligible for promotion, as Ealing Trailfinders did not meet an RFU deadline, despite having a groundshare in place.