Service of notice: prescribed modes and deemed-service rules determine when GST communications are treated as served. The Act prescribes authorised methods for serving decisions, orders, summonses, notices or communications: personal delivery to the addressee or authorised representatives, registered/speed post or courier with acknowledgement, e-mail to the registered address, availability on the common portal, local newspaper publication, and affixture at the last known business or residence or on the issuing office's notice board when other modes are impracticable. A communication is deemed served on the date it is tendered, published or affixed; postal dispatch is deemed received after the normal transit period unless disproved.