Hi Liz, great question!
In QuickBooks, the billable box should be used whenever you have purchased an item on behalf of a client and you expect to be reimbursed for the purchase. Checking the “billable” box and selecting the client that needs to be billed will do two things:
Create an unbilled item that you can add to a future invoice.
Set up a reminder for that customer so the next time you go into QuickBooks to create an invoice for that customer, you receive a notification from QuickBooks that the customer has “unbilled items”. You can choose to add them to the current invoice that you are creating or you can select no if you prefer to bill them at a later date.
Thank you for reading!