Thanks for joining us here, postit. Allow me to share details about using the Discount feature in QBO. 

When a discount is applied to a transaction, sales tax is calculated based on the price after the discount has been applied rather than on the original price.

Please note that the discount can only be applied to the entire invoice in QuickBooks Online and not on a per-line item basis.

If you need to calculate a discount based on a specific item, you can use a sub-total as a workaround. Please refer to these articles for more detailed information about this feature:

• Add A Discount To An Invoice Or Sales Receipt In QuickBooks Online
• Use Discount And Subtotal Items On An Invoice

Although, you can override the amount of sales tax when creating sales transactions. Here's an article as a guide: Override Sales Tax On Transactions In QuickBooks Online.

However, I would recommend consulting with your accountant for further advice before adjusting the sales tax. Their expert advice will ensure you remain compliant with all relevant guidelines and regulations when it comes to tracking sales taxes.

You may want to review or bookmark these articles related to sales tax: 

• Edit Sales Tax Rate In QuickBooks Online
• Create Or Delete A Sales Tax Adjustment In QuickBooks Online

You can use them as additional resources when collecting and reporting sales taxes in QuickBooks Online:

Please don't hesitate to return to the Community whenever you need additional support, postit. We are available 24/7 to jump in and offer our help when you need it.