off course you need to charge GST. SEZ Invoices--With Payment of Tax where as supplying to SEZ unit if you have already obtained LUT (letter of Undertaking Bond ) then the taxes are nil -- Zero rated.
21 June 2018
If you have LUT bond then Show the basic value and Next you will enter in the Tax column as"Export Supply under LUT bond" and show the tax value as Zero...
If you have not LUT bond then GST will be charged on the Invoice. But, Payable by Yourself. The SEZ customer not give the Tax amount to you...