Is their a way to add a percentage charge for supplies to an invoice total in QBO?

Yes, there's a way to create a percentage charge to invoice total. However, this requires a workaround, @threerivinc.

First off, let's create a new service item named for the charge so we can use this to calculate the amount of charge.

1. Go to the Gear icon.
2. Select Products and services.
3. Click on the New button and select Service.
4. Enter the name of the charge.
5. Set the sales price/rate to the decimal percent for the charge. For example 75% = 0.75.
6. Select the specific income account.
7. Select Save and close.

Once done, you can add this item to the invoice. Then, enter the subtotal amount as the quantity.

1. On the Invoice page, fill in the necessary information.
2. After you enter the products and services, click the Add subtotal button at the lower-left corner.
3. On the next line item, add the percentage charge item.
4. Then, under the QTY column, enter the subtotal amount.
5. Select Save and close.
   
   

The screenshot below shows you the 2nd to 5th steps.


After your customer pays their invoices, read through this article to record them: Record invoice payments in QuickBooks Online.

Please let me know if you have additional questions or concerns. I'll be here every step of the way.