Article 31 details the specific methods for serving notices on taxpayers. These include: personal service to the Principal Officer, sending to the last known address via post, or delivery to a person specifically designated by the taxpayer to receive notices. For joint ventures, notices are issued in the name of the company or Principal Officer. Importantly, all notices of assessment orders must be sent via registered post. This variety of methods ensures that the Authority can reliably reach the responsible parties while providing a clear paper trail for legal enforcement.