Bills

If your company purchases directly from Microsoft, you'll see the invoices for your services on this page. You can use the drop-down menu to access This month, Last month, the Past 3 months, Past 6 months, Past year, and Specify date range quickly. If you want more detailed breakdowns or to view inpidual invoices prior to the last month, click on View details. You can also view the invoices as PDFs:

Bills page

If you purchase your Office 365 from a Microsoft partner through the CSP program, another reseller, or through a specialty program (for example, there is special handling for nonprofits, as well as annual purchases through MS Open), you will not see anything here. The Bills page only shows Microsoft invoices.