How do i add custom fields to.. invoices estimates and customers? and can i split receipts and have some line items billable to client and some line items not billable?

Hi there, 

Since this is your first post in the Community. I'd like to give you a warm welcome. 

QuickBooks Online makes it easy to add a custom field to your invoice and I'd be glad to show you how.

To do this, follow the steps below: 

1. Click the Create (+) icon at the top of the account.

2. Click Invoice.

3. Once the invoice creation screen appears, click the small Gear icon at the top of the page.

4. Click Add another field.

5. Enter the name of the field you'd like to add.

Here's a screenshot to help guide you to the right place.

Once you set up a custom field, you can enter the necessary information on the invoice creation page. For more info on how to customize an invoice or other sales forms, check out this helpful article: Email and customize sales form.

Let me know if you have other questions. I'm here to help.