Hello there, @Mary102.

You'd want to create a retainage payable account on your Chart of Accounts. Let me show you how:

1. Go to the Accounting menu.
2. Choose the Chart of Accounts tab.
3. Click New.
4. Under the Account Type drop-down menu, select Other Current Liabilities.
5. On the Detail Type drop-down menu, choose Other Current Liabilities.
6. In the Name field, enter Retainage Payable.
7. Click Save and Close.

Once completed, you can create a retainer service item. You can use it in creating a sales receipt or an invoice to record the amount you've received from your customers. Here's:

1. Choose the Gear icon ⚙.
2. Select Products and Services.
3. Click New.
4. From the Product/Service information panel, pick Service.
5. Enter a name for the new product or service item (ex. Retainer).
6. From the Income account ▼ drop-down menu, select Trust Liability Account.
7. Click Save and close.

You can read through this article for more  detailed steps: Record a retainer or deposit.

Leave a comment below if you have other questions or concerns about tracking your income and expense transactions. I'm always here to help.