Gstr1 late filing march 2020 retunr file in Oct 2020

Filing your March 2020 GSTR1 return in October 2020 means your vendor cannot claim Input Tax Credit (ITC) for your invoices, as the September return due date has passed. If your vendor has already claimed the ITC, they will need to reverse it and pay interest. You may face a situation where you've paid the tax, and your vendor demands the tax amount again, potentially leading to double payment for the same invoice.