1099 Vendor Summary Report
If your Vendors inside QuickBooks are properly flagged as "eligible for 1099", running a 1099 Summary Report for the prior year is simple....
Go to Reports-->Vendors & Payables-->1099 Summary
Make certain your filter's and 1099 Options are set correctly:
The report results should provide a summary of payments by vendor which have exceeded the 1099 thresholds. However, the results will only show vendors which have had the "eligible for 1099" check box marked on the vendor's Tax Settings. Therefore, before proceeding it might be wise to take additional measures to scrutinize all payments to all vendors.
Now that you know how much you paid your 1099 Vendors in the prior year; you'll want to review your 1099 Vendor Details to spot any missing details before exporting.