01 May 2020
You contact your jurisdiction professional tax officer he may help you EC they would have collected details while registering RC, if you have made payment for earlier year details check bank to give details of payment or challan you can get EC in Bank challan.
08 May 2020
You may have the details of the in Payment Challans as already mentioned, Xerox Copies, any email correspondences, SMS alerts, or the details might also have with Tax Consultant if any. I think at the time of migrating to GST it asked all details of previous registrations if applicable you may have this details in the soft copies of GST Applicable and GST Portal.
If you can not find the same you have to approach local office as per your jurisdiction.
CAclubindia
