I need to add a 'deposit' tab after my subtotal on invoices that are converted from estimates.

Welcome to the QuickBooks Community, sales332. You can add a deposit section to your invoices by enabling the Deposit feature in your Account and settings. 

Here's how:

1. Click the gear icon.
2. Under YOUR COMPANY, select Account and Settings.
3. Navigate to the Sales tab, and in the Sales form content section, click Edit ✎.
4. Turn on the Deposit option.
5. Click Save, then Done.

Once the Deposit option is enabled, it will automatically appear on your transactions.  

For more information about managing deposits on invoices, check out this article: Manage deposits on invoices in QuickBooks.  

If there’s anything else we can help you with, feel free to leave a comment below. We’re always here to assist you!