You can call or write to Épargne Placements Québec, or fill out the Change of Address Notification Form, which is available at banks and caisse populaire branches (also included with your annual interest cheque).
To have your address changed, you must provide:
Note
To receive the interest cheque at the right address on June 1, the holder must notify Épargne Placements Québec of his or her new address before April 15, in the case of Series E-95 or earlier products, and before May 15, in the case of Series E-96 or later products.