We are into works contractor for govt departments. Once we submit the invoice to the department it may take a long time to receive payment. so we are uploading invoices to the GST site once we received payment from the department. now the thing is, from this month on-wards GST rate is changed from 12% to 18%. we submitted invoices for 12% to the department. but we are going to upload invoices to the GST site in the future once we received payment from the department. now how to adjust that differences because it is difficult to bear 6% from hand. The government will not pay 18%. it only pays as per the bill.