The option to import invoices with sales tax set up in your account into QuickBooks Online (QBO) is unavailable, Charles24.

You'll see this error message if you have Automated Sales Tax (AST) set up in your QBO account and Importing Invoices isn't supported for customers with AST yet. Rest assured that our developer team is still working to make that function available to those customers. You can visit this article for more details about this option: Import multiple invoices at once in QuickBooks Online.

In the meantime, you'll want to consider looking for a third-party app that allows you to import your invoices with sales taxes into QBO. You can also visit the QuickBooks App Center website and search for a third-party application that best suits your business needs.

Additionally, you can check out this article to learn how to personalize the appearance by adding specific info to your sales forms in QBO: Customize invoices, estimates, and sales receipts in QuickBooks Online.

I'm all ears if you have other concerns about the system's features and managing your invoices and other sales forms in QBO. Take care, and have a great day!