Problem
You have an inventory part in QuickBooks named "Tax" that also has inventory connected with it. Troubleshooting is to create a "tax" service in QB but you cannot due to that service already existing. You get the QuickBooks Error "There was an error when saving a Bill. QuickBooks error message: You have no items or one or more of your amounts is not associated with an item. Please enter an item."
Solution
Change the tax item to a service
When exporting bills to QuickBooks, ServiceTitan is creating a tax item with an item type called "Other Charge" and names it "Tax". Items created automatically by ServiceTitan will be created as a "Service". The solution is:
Change the item to "Service" in QuickBooks Desktop.
Note: Leave the account as "Expense".
On the ServiceTitan Accounting Page, pull up the batch with this error > Right Click + Reload to hard refresh > Export the Batch.
