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The best way to send one invoice that allows your customer to make two payments is through a partial payment.

A partial payment lets your customer pay part of the invoice now and the rest later. Please create one invoice with the total amount all the items, then apply the partial or deposit, and then the remaining balance until the payment is complete.

Here's how to Record Partial Payments:

1. Create a single invoice listing with all the items the customer needs to pay for.
2. Go to + Create, select Receive Payment, and choose the customer.
3. Mark the correct invoice, and in the Payment column, enter the partial amount.
4. Click Save and send.

Please see the sample screenshot:

You may also check this article for more details: Record invoice payments in QuickBooks Online.

You can also check your invoices, estimates, sales receipts, and their statuses by going to All Apps, then selecting Sales & Get Paid, and clicking on Sales Transactions.

Please leave us a response if you have other questions or concerns.