How do I charge 50 percent of the line item on my invoice?

Let me welcome you here in the Community, @joemblaz.

To charge 50 percent of the line item on your invoice, you can turn on the Progress Invoicing option from your settings. You can follow the steps below to turn this feature on.

1. Go to the Gear icon, then Account and Settings. 
2. Select Sales.
3. Open Progress Invoicing and tick the checkbox. 
4. Click Save and Done. 

By following the steps mentioned, you can now successfully charge any invoices by 50percent.

You can check this article to learn how to receive and record payments in QuickBooks Online: Record invoice payments in QuickBooks Online.

If you have other questions regarding invoices, you can return them here by posting your concern to the Community forum. We will always be glad to assist you.