Let QBO do the work for you. To make it easier to add expenses to your billing when invoicing clients, add your customer’s name and click on the “billable” box when you enter line items into your expenses into QBO. This will help with both job costing and creating invoices for your clients.

Example:

By applying the Billable and Customer fields in that expense, it will look like this when you create your next invoice to that customer:

See how the expenses appear to the right? You can then click and choose which of that customer’s billable expenses to add.

If you do not click “Billable” but still enter the customer name associated with that expense, like below, the entry will still appear in reports associated with the customer/project to help keep track of your costs.