QB Issue Resolution:

Unlike desktop, there is no percentage line item in QBO

 

There is a work around though

create a service item named discount and link it to a sales income discount account, set the rate to a negative %, -10%, when you click out of the rate box QBO will change that to -0.1 (or you can just enter a negative decimal number = to the percent of discount)

 

use that item on the invoice or sales receipt, enter the amount to be discounted as the qty

the resulting math will be a negative 10% of the amount.

Resolution for Issue 'How to add a item as a percentage instead of $ amount' available: Yes (Solved).
Source: Intuit Community forum.

How to add a item as a percentage instead of $ amount: this issue or error code is a known issue in Quickbooks Online (QBO) and/or Quickbooks. Support for this issue is available either by self-service or paid support options. Experts are available to resolve your Quickbooks issue to ensure minimal downtime and continue running your business. First try to resolve the issue yourself by looking for a resolution described below. If it is a complex issue or you are unable to solve the issue, you may contact us by clicking here or by using other support options.

Support for discount account
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