29 October 2017
The transaction pertains to the period when reverse charge under section 9(4) was effective. You would be required to issue self-invoice and the same is also required to mention in your GSTR-2.
The content of Self invoice would be similar to your Tax invoice except certain changes.
31 October 2026
Under current law, purchases from unregistered persons do not attract RCM generally; Sec 9(4) now applies only to notified cases (e.g. real-estate promoters short of the 80% registered-purchase norm), and Sec 9(3) only to notified goods/services. Self-invoice u/s 31(3)(f) is needed only where RCM actually applies.