Hello there and thanks for posting here in the Community space, redbigfoot.

QuickBooks Online calculates sales tax based on location using the criteria below:

• Your customer's tax-exempt status
• Where you sell and where you ship
• What you sell

This is the reason why it is impossible to turn off the Based on Location tax feature. It is performing as intended. You'll have the option to set up a custom rate as an alternative if the third-party program doesn't have this default function.

Here's how:

1. Open the Taxes menu.
2. Click on Sales tax settings.
3. From the Custom rates section, choose Add rate.
4. Click on Single or Combined.

Once done, you can manually select the tax rates from the Based on location dropdown on the invoices created from the other system. Feel free to visit this link for more details: Use custom rates to manually calculate taxes on invoices or receipts in QuickBooks Online.

I'm also including the following useful guides to assist you to keep track of and manage your reports in QBO:

• Run reports in QuickBooks Online
• Customize reports in QuickBooks Online

If have further questions about taxes, please let us know. We're available to help you at any time.