You can safely renew your annual pass before it expires. The new end date of your annual pass will then be exactly 1 year after the current end date of your annual pass. If you renew your annual pass after it has expired, the renewal takes effect immediately and the new end date of your annual pass will be 1 year after the renewal date.
Would you like to benefit from the advantageous renewal rate? You can do so up to 1 month after the end date of your annual pass. If you renew your annual pass more than 1 month after the end date, you can renew it at the standard rate of a new annual pass.