During an interview on the AEW Unrestricted podcast, Cody Rhodes talked about AEW's contract tier system:

"Agree to appear is a tier 0 meaning you'll get a bonus, which Tony's super super generous. If you ask some of these extras what they're making for being there (Rhodes takes a moment), my dad would have lost it. But he's right. It's COVID era. They have no other work. There's no indies. Tier 0 is just a signing bonus and exclusivity to us in terms of we get a first option on you I believe is how it works, and we guarantee you x amount of dates, five dates."

"The exclusivity thing is case by case, but we guarantee you x amount of dates. The goal is you don't want to pay someone agree to appear, Chris Harrington would handle this much better than I am, you don't want to keep giving them their weekly, their weekly, their weekly, their weekly vs. tier 1-ing them, which is our base contractor agreement. That's another thing, we're just talking about Tony, we built a middle card and a lower card. We have tier 1's, tier 2's, tier 3's, tier 4 and tier Jericho." 

Thanks to WrestlingInc. for transcription.