The KPI's you mention are great if all you want to do is measure the sheer amount of work done. They don't do much if you're trying to understand the work quality or how the department is furthering the company vision. I recommend that instead of viewing the accounting department as a production or cost center think of it as a service center. In what ways does it serve and support the other departments? How does it help the company solve problems (not just accounting problems)? If you can answer those questions then you're getting somewhere. You can devise a system for measuring and tracking accounting's contribution.