Can I make an Invoice and put it on "hold" We have customers that we start an invoice with but then we come back later and do follow up work.

Thank you for posting here, @prindtina.

Currently, the option to put invoices on hold in QuickBooks Online (QBO) is unavailable. As a workaround, you can create an Estimate and when completed, copy the transaction to the invoice. The invoice is used for the final sale while estimate is a non-posting transaction. 

Here's how:

1. Go to the +New button and choose Estimate.
2. Choose the name of the customer under the Customer field.
3. From the Product/service section, pick the items, and hit Save when done.
4. When you'll need to do follow-up work, go to the Sales menu.
5. Click All Sales tab and hit the Filter drop-down menu.
6. In the Type drop-down, select Estimates and Apply.
7. Look for the Estimate of the specific customer to edit.
8. If finished and there's nothing to add or edit, tap Save, and select the Create invoice option.

For more details, you may check out this article: Convert an estimate into an invoice in QuickBooks Online. 

Also, if you have customers you invoiced regularly, you may consider reading this article to help you set up recurring invoices that can be sent automatically to them: How to create a recurring invoice and manage recurring transactions. 

If you have other concerns with creating an invoice, let me know by adding a comment below. I'll be right here to help whenever you need one. Have a good one.