How do I apply a billable expense to a sales receipt?

why in the world is this not an option?!?!?! again, making numerous steps when it shouldn't have to be so complicated. UGH

Hello there, 335Ocean.

By default, a billable expense is assigned to an invoice because it is not paid right away. For example, you take a taxi to meet your customer, and they will reimburse you for the travel expenses. You can record your fare as a billable expense and then add it to their next invoice.

You can check this article for more information: How to enter billable expenses.

Please let us know if there's anything else you need help with QuickBooks. Thanks.

It's super cool that you answered this, but your answer doesn't actually address the underlying issue...

As an accountant and ProAdvisor, this is something I deal with all the time and, frankly, it's a limitation of the software that needs to be fixed. 

Let me first acknowledge your answer: yes, you might invoice your client for reimbursable taxi expenses incurred while meeting with them. Alternatively you may have an agreement with your client to automatically bill them their statement balance at the end of each month and ... this is where the issue of not being able to add billable expenses to a sales receipt becomes a huge issue.

Invoicing is not the only way, nor is it necessarily the preferable way, to bill a recurring client you've established vendor terms with. The sales receipt is a totally acceptable way and is, indeed, preferable in many scenarios.

So, to fully address the OP: yes, billable expenses should be available to be added to a sales receipt and, no, QuickBooks Online does not currently offer this functionality. This is an unfortunate limitation of the software that should be corrected.