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@Bill1626  RE: Does anyone know if QuickBooks assigns a unique id number to each customer that is created in QB's Ent. 23? If they do, is there any way to see or print or export those id numbers?

Yes, it does assign and use ID numbers to all list records, including all types of Names.

It isn't possible to view the numbers within QuickBooks, but you can export the customer list to see them.

To do this, export the list to an IIF file. Start at File | Utilities | Export | Lists to IIF files...

Once created, open the IIF file in Excel or other spreadsheet to see the numbers. They're in the REFNUM column of the CUST record (and most other list record types):