Circular No. 69/43/2018-GST dated 26th October 2018 
Cancellation of Registration -Clarification by CBIC- Circular No. 69/43/2018-GST dated 26th October 2018:
REG-16 is required to be filed with in 30 days of occurrence of the event warranting the cancellation. Circular has advised not to reject registration application on this ground where exact day could not be identified for occurrence of the event warranting the cancellation.
REG 19 order for cancellation need to be issued with effective date, same as the date from which the applicant has sought cancellation in FORM GST REG-16.
GSTR-10 need to be filed by the assessee within three months of the effective date of cancellation or the date of order of cancellation in REG 19. However last date for furnishing of FORM GSTR-10 by those taxpayers whose registration has been cancelled or before 30.09.2018 has been extended till 31.12.2018 vide notification No. 58/2018 – Central Tax dated the 26th October 2018.
In case the final return in FORM GSTR-10 is not filed within the stipulated date, then notice in FORM GSTR-3A has to be issued to the taxpayer. If the taxpayer still fails to file the final return within 15 days of the receipt of notice in FORM GSTR-3A, then an assessment order in FORM GST ASMT-13.
Refer: Circular No. 69/43/2018-GST dated 26th October 2018