If you're looking to race outside of the country then you will need a UCI/international license no matter your age or category. If however you're looking to compete at a UCI event here in the United States there are only three categories that require you to hold a UCI license, Junior 17-18, Under 23, and Elite.

Racing Licence holders are eligible to participate in national competitions such as National Championships and National Series events and be eligible for Provincial and National selection. Riders who race in the UCI racing categories, Junior, Under 23 and Elite, earn valuable UCI points contributing to Individual and National Ranking.

The UCI issues racing licenses to riders and enforces disciplinary rules, such as in matters of doping. The UCI also manages the classification of races and the points ranking system in various cycling disciplines including road and track cycling, mountain biking and BMX, for both men and women, amateur and professional.