We provide consignment services. In a senerio where we provide 10 product A and every month our customer sold 2 and paid for it, how do we track the remaining inventory?

Hi there, romjan-hoque-xtr.

Thank you for visiting the QuickBooks Community. I'll share steps so you're able to track and send to your customer how many items are left unpaid and the quantities.

You can create an estimate entry in QuickBooks Online to track the quantity of the products of the unpaid amount for your clients. This way, you could send them how many items and quantities are left unpaid. Then once it's already sold and paid, you can now create an invoice andreceive the payment. Please note that estimate is to give your customer a quote, bid, or proposal for work you plan to do. This helps you start discussing details with your customer.

 Here's how to create an estimate:

1. Click the + New button.
2. Choose Estimate.
3. Select a customer from the Customer dropdown.
4. If the work has already started, select a status from the Pending dropdown. This is optional.
5. Set the Estimate Date and the Expiration Date.
6. Enter the products and services you plan to sell.
7. Enter any other info you need.
8. Hit Save and send.

You can refer to this article to view additional information: Create and send estimates in QuickBooks Online.

Please refer to this article to view details on how the Sales page gives you a great at-a-glance view of the status of sales transactions, open invoices, and paid invoices: View sales transactions.

You can always leave a reply below if you have other follow-up questions about tracking the quantity of the products. I'm always here to help.

@romjan-hoque-xtr 

Another option, consider having an additional app to manage your consignment business.