It is now mandatory (since January 2006) for all horses and riders to be registered with the FEI before competing at an International event at home or abroad. This is regardless of whether they hold an existing FEI Passport or have already previously competed at International level.
Please see the FEI website for more details
If you are planning on competing at an FEI competition, please contact your discipline directly in order to apply for FEI registration for both yourself and your horse/s.
Registrations are annual and run from 1st January each year.