Service of notice: multiple permitted modes and deemed service on tender, publication or affixation under GST law. The Act permits service of decisions, orders, summonses, notices or communications by direct delivery, registered/speed post or courier with acknowledgement, electronic mail to the registered address, availability on the common portal, publication in a local newspaper, or, if impracticable, by affixing at the last known place of business or residence or on the officer's notice board. Deemed service occurs on the date of tender, publication or affixation; registered or speed post is deemed received after the normal transit period unless the contrary is proved.