Help I am unable to reconcile my GSTR1 last month The HSN wise summary has negative values for quantity. But all the material has stock and the dates are a month earlier.

Hello,

Welcome to QuickBooks Community.

The sale quantity is shown as a negative number but this doesn't alter the sale value. So, you don't need to worry about that. If there's a discrepancy in the Value, Taxable Value, and Tax columns, please let me know. In that case, the QuickBooks Support Team will be able to help you out. 

I hope this helps.