How do I raise an invoice for a billable expense?
There are two ways to raise an invoice for a billable expense. You can do this directly from the expense or create an invoice and include the unbilled expense.
To create an invoice from the expense:
- Go to the Purchases module on the left sidebar and click Expenses. 
- Select the expense you have marked as billable and click the Convert To Invoice button.  
- A new Invoice will be created with the expense details. 
- Enter other required details and click Save and Send to send the billed expense as an invoice to your customer. 
To add an unbilled expense to an invoice:
- Go to the Sales module on the left sidebar and click Invoices. 
- Click + New in the top right corner to create a new invoice. 
- Select the customer for whom you recorded the billable expense. 
- The unbilled expense associated with the customer you have selected will be displayed below the item table. 
- Click the unbilled expense to add it to the invoice.  
- Add other necessary details and click Save and Send. 
The billed expense will be sent as an invoice to your customer.