The Directorate General for Language Policy (DGPL) holds official examinations each year. These are announced in the Official Journal of the Government of Catalonia (DOGC), usually before the end of January. The exams usually take place in May or June and the registration period is at the start of the year. The DGPL website contains all the information on these exams.
For more information about language certificates, go to: http://www.intercat.cat/es/info/certificats-oficials-catala.jsp
If you have studied in Catalonia or have any Catalan qualification, diploma or certificate issued by an official body outside Catalonia, see the DGPL’s list of equivalent qualifications to the official Catalan certificates
The end of course certificates (Basic 3, Elementary 3, Intermediate 3, Sufficiency 3, Superior C2) issued by the Consorci per a la Normalització Lingüística (CPNL) are official and are equivalent to the certificates issued by the Directorate General for Language Policy (DGPL).
If you live outside Catalonia you can find where and when official examinations will be held on the website of the Institut Ramon Llull (IRL). The examinations can be sat by anyone of any nationality who is aged fourteen or over on the date of the test, and who wants an official accreditation of their knowledge of the Catalan language without having studied an official course.