You don't need a card to do some competitions others you do. The card is essentially an extra 30 bucks you're throwing at the IBJJF. Kids, Browns, and Blacks Are required to have the card to be eligible for all competitions. Blues, and Purples don't need a card and can just register. But if you have the card and you renew every year the paperwork when you apply for black belt and other stuff like that won't be as complicated because the IBJJF will recognize your ranking every time you renew every year. It's some bullshit. I didn't get my card for the Chicago tournament and I can sign up. The best way to see if you need it is if you go and click on the tournament you want to register for and follow the steps to sign up. It'll stop you if you need the card. Chances are you only need your car for Euros, Worlds, and the one in brazil.