Assessment under section 63

 In section 63:
Mentioned that assessment of cancelled dealer who was liable to pay tax.for relevant period
Please clear that this relevant period is after the date of cancellation or prior to the date of cancellation.
Because prior to the date of cancellation,the dealer act as registered person and  Non-filer of gstr return.s o at that period assessment u/s 62 will apply.
Than section 63 will apply in which period.
liabilty due after the date of cancellation?