How do I instruct a customer how to pay 50% on an invoice?

Hello, loganwrapitupkc.

I'll show you a way on how you can instruct your customer to pay 50% on an invoice. 

You can add the instructions on the email before sending the invoice to your customer. For a brief explanation on how the customer can pay 50% on an invoice, they'll be given the option to edit the amount.

They can simply click the Edit link on the "Pay invoice" screen. This is what it looks like in their end: 

That said, here's how you can relay the instructions to them:

1. After creating an invoice, click the Save and send button.
2. Under the Send email section, enter the instructions in the Body text box.
3. Review the details of the invoice.
4. Once done, click Send and close. 

You can also make this as a permanent template for your emails: 

1. Click the gear icon, then choose Account and settings.
2. Go to the Sales tab.
3. Expand the Messages section.
4. Enter the instructions in the Email messages box.
5. Click Save then Done. 

If you need help recording your customer's payments, please check the steps from this article: Record invoice payments in QuickBooks Online.

Want to know how much you've earned from your sales? You can pull up a variety of reports such as the Profit and Loss report. Check out the articles here for a guide on how to run them. 

I'll address other concerns you might have for QuickBooks Online. Just let me know the details down below. Take care out there.