Each month as part of the month end reconciling process you will want to confirm that your GL Accounts Payable account ties to your payables sub-ledger.
First you will want to generate the Historical Aged Trial Balance Report in Purchasing. To do this go to: Purchasing > Reports > Trial Balance. Reports: Historical Aged Trial Balance. Options: Month End or default (this will depend on your report options settings). In the Report Options window you will want to select the date to Print/Age as of, select the last date of the month you are reconciling. I recommend generating this report In Detail (mark the In Detail box), but you could generate it as a summary report.
If you generate the report in detail, you can review the transactions that are listed for each of your customer, as well as their total balance.
On the last page of the Trial Balance will be the Grand Totals. The GL Accounts Payable account should tie to the Due Amount on this report.
You can see the GL account balance two ways. You can view it in the Summary Inquiry, or generate it in a financial Trial Balance. To view the balance in Summary, go to: Financial > Inquiry > Summary. Enter the Accounts Payable account number and tab. This will bring up the period balances for each period. The period balance for the month you are reconciling should tie to the Historical Aged Trial Balance.
To create a trial balance for this account, go to: Financial > Reports > Trial Balance. Report Options: Detailed, Options: Month End or Default. In the Report Options window, enter the restrictions for the date range and the Accounts Payables account.
Generate the report. The Ending Balance is the number that should tie to the Balance of the Historical Aged Trial Balance Report.
If your GL account does not tie to your Historical Aged Trial Balance, you will need to discover why and make corrections. You can do this by using the Reconcile to GL routine for Accounts Payable.