we had cancelled out gstin due to change in constitution of business and issued a new gstin for the new pan, we were holding stock on the day of cancellation of old gstin, we dont want to reverse the tax help but to give that tax credit to the new gstin, do i need to bill the new gstin and nill my stock for gstr 10 and if so, what would be late fees and penaly as the old gstin was cancelled on 1st july 2018. can i bill it now in back date, please advice