I understand that you're facing an issue where your non-taxable sales tax is showing as negative when paying taxes in QuickBooks Desktop (QBDT), CSM. 

I've tried to replicate it here on my end by following the steps outlined in the article, but I am not seeing a negative balance when making sales tax payments in QBDT.

We can review the transactions from the Customer profile and ensure that we select the non-taxable items. Here's how:

1. Click on the Customers menu in the top menu bar. 

2. In the dropdown menu select Customer Center.

3. Choose the customer whose profile you want to access. From there, you'll be able to see the transactions. 

 Check out this article for your guide when you're ready to pay your sales tax after fixing the negative amount in QBDT: Pay sales tax. 

To learn more about sales tax, and sales tax liability reports, you can check these articles:

• Set up sales tax in QuickBooks Desktop
• Sales Tax Liability Report

You can always drop by again if you have other questions about managing sales tax.  If you have trouble recording your entries, let me know and I'll work with you. Have a great day.