How can I add a billable service to a client's account without billing them yet?

You can use the Estimate feature to track the filings that you did for your clients, Y10 Tax.

Then, convert them into invoices once you're ready to send them a bill. Since en estimate is not a posting transaction, it will not add to the client's total balance. Here's how:

1. Click the + New button and select Estimate. 
2. Enter all other details of the transaction including the name of the client, date, and the service that you're offering.
3. Click Save.

Once you're ready to create an invoice, you just need to open the Estimate and click Create invoice in the upper-right hand of the transaction. Here's an article for more details: Convert An Estimate Into An Invoice In QuickBooks Online.

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