"Something's not quite right. One or more charge lines do not have a tax code associated with it. Please assign a tax code for those lines. What is the solution of above?

Hi there, info-aiglon-in.

You'll get this error message when a tax code is not selected from the Tax column when saving a transaction. To resolve the error, make sure to add a tax code in each line.

Here's a sample screenshot for reference:

Moving forward, you can select a tax code in each product, so it auto populates when you add the transaction.

Here's how:

1. Go to the Gear > Products and services.
2. Click the Edit link of the item you want to modify.
3. From the Tax drop-down menu, select the appropriate tax code.
4. Hit Save and close.

I've got this sample screenshot for reference:

You can also read this article: How do I set up sales GST/VAT rates and use them on forms? (International QBO).

Should you have any additional questions or other concerns with QuickBooks, please let me know in the comments below. Thanks.