Which of the following components can be billed to a customer under a project?

The correct answer is that expenses marked as billable can be billed to a customer under a project. In QuickBooks Online, users have the ability to categorize certain expenses as billable. This means that when these expenses are incurred, such as materials or other costs associated with a project, they can be charged directly to the customer regardless of the nature of the expense.

When an expense is marked as billable, it is linked to the customer and can be included in invoices, allowing businesses to recover costs directly tied to specific projects. This feature enables better project management and profitability tracking, as it ensures costs are accounted for and billed appropriately.

In contrast, fixed costs and labor costs by themselves are not automatically billable unless they are explicitly marked as such. Additionally, stating that all costs are absorbed by the business ignores the capability of the software to track and manage billable expenses effectively, leading to possibly significant losses if a business does not recapture these costs from clients.