Horses entering CVI 3* or a CVI outside of Canada must have an FEI Passport.  Horses must be micro chipped in order to recieve the Passport and FEI ID number.  The FEI passport currently costs $348 and you can apply for it here:

FEI Passport Apllication Form

Canadian Horses entering a CVI 1,2* in Canada require an FEI ID Number, and a Canadian EC National Passport.  Horses require a micro chip for the FEI ID Number.  The EC National passport costs $150 and you can get the application here:

EC National Passport Apllication

All horses entering a CVI must have all their vaccinations up to date and entered into their relevant passport.