The Organizer badge is awarded for the first retag, but you need 500 reputation points before you can retag questions. Having said that, when I click on the Organizer badge, there are lots of people who have been awarded this badge with less than 500 reputation points. I must be misinterpreting when the badge is awarded. So my question is the one in the title: How is the Organizer badge awarded?
I have previously added tags and deleted tags on questions that I have asked, but I haven't been awarded the badge. I'm not complaining, I just don't understand how it works.
I think I have the answer. I have an organizer badge and yet my reputation is less than 500. I did it by adding a tag to a question (not mine) that was community wiki.
Just for the record: I recently asked a question on MO. Shortly after I deleted one tag and added another, but I still wasn't awarded the Organizer badge.