This issue is partly resolved for me.
It now calculates the sales tax correctly, but only if I add the billable expense (unbilled income) in a specific way. Let me explain, as there are two ways I typically add those to an invoice. One will work correctly and the other will not. I am unsure as to why it doesn't work both ways.
Hopefully Intuit can remedy the situation further so that it always works correctly.
Scenario #1:
Create a New Invoice using a blank invoice and then add the customer name. This will then give a list of suggested items to add to the invoice from the unbilled income (billable expenses) attached to that customer.
When you add these to the invoice they will work exactly as expected, and the sales tax will calculate accurately for both the product line item and the markup line item (which is a hidden item from the customer).
Scenario #2:
Starting from the list of unbilled income select "Create Invoice" from an unbilled income product/service.
This will then start a new invoice and automatically fill in the customer information. It will also give you the option of adding other "suggested items" to the invoice. However, the tax will be calculated incorrectly for the line item that you added initially, but all of the additional added from within the invoice will be calculated correctly.
So, in conclusion this issue is almost resolved.
I would like to have more peace of mind that when I add items to an invoice that the math is working correctly.
Simple math like tax percentage should not be something that is failing. I understand that the tax portion is not as simple as the math, but when I have marked it as taxable and I even had changed it to not use the Automatic Calculation and it still wasn't doing the math correctly, there is a major issue. Especially as Intuit and Quickbooks Online pushes the users to utilize more "Automated" tasks taking the user out of the responsibility of entering and verifying everything prior to sending invoices, payments, etc. and asks us the users to trust that it is doing the job correctly.
