Is vat lumpsum rates are applicable in gst

Any retailer businessman cover under vat he file & paid vat amount as lumpsum , return file quaterly his annually sales before discount value is Rs.60,00,000 lakh. Now they covered under gst . Is there any chage in to lumpsum vat rate amount and gst vat return filing procedure.He doesn't provide any tax invoice.

Can someone have replay?