Can I exclude open invoices (not yet sent out) from client statements? & Is it possible to add an ageing schedule to a transation statement?

Hi there, @hansiem.

You can exclude them by deleting the invoice transaction. Although, you can create an estimate and by the time the work is done, you can send an invoice easily by linking your estimate. I'll show you the steps on how to do that.

Step 1: Create an Estimate.

1. Go to the Hamburger icon and select the New + button.
2. Select Estimate and enter the details.
3. If your customer has an email, click Send later.
4. Select Save and close.

Step 2: Create an Invoice and link your Estimate. (Please do this when the work is done)

1. Go to the New + button and choose Invoice.
2. Enter the Customer's name.
3. On the right pane, there will be an estimate transaction available to be linked, click the Add button.
4. Verify the details and then click Save and Send. 

I added a screenshot for your additional reference.

Once done, you can create a Transaction Detail by Account Report, then you can customize it to see the specific customer, the transaction amount with its balances. Here's how it looks like.

For future reference, you can also check out this article to help you more about tracking your invoices: Set up and send progress invoices in QuickBooks Online.

Count me in if you need anything else. I'll be here to help you. Stay safe always.