can some one help with gst summary cash report not matching profit & loss statement

ajauto 

The GST cash report is just that, monies collected and paid for any given period. The profit and loss is an accrual report and shows invoices and bills for a given period regardless of their payment status.

If you look under Reports> Accounts> Small Business Entity you will find Profit & Loss Cash Basis. You should find better agreement with your GST report.