The Sales tax report is not calculating all sales tax from all paid invoices! it is showing much less than it supposed to, any idea how to solve this?

Hello there, @PAWS-INN. I’m here to help you ensure that your sales taxes are calculated correctly in QuickBooks.

After you've set up sales tax in QuickBooks Online (QBO), the total tax rate for each sale is determined as follows:

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

To fix the sales tax issue, let's check first your customer's status and make sure that they are not tax-exempt. Once done, let's now verify that your products and services are taxable. You can also visit this article to help you determine if your sale is exempt from tax in QBO: Conducting nontaxable sales. 

Then, to give you insights about sales tax calculation in QBO, feel free to open this link: Learn how QuickBooks Online calculates tax. 

If you ever want to keep track of your customers' outstanding balances to determine how much is still due and how long they’re past due, you can run the accounts receivable ageing report in QBO.

If there's anything else I can help you with your sales tax calculation concerns, feel free to post a reply below. I'd be happy to assist you further. Have a good one.