Accounting is the basis for managing business entities and is defined through four approaches, and consists of a quality information system that serves as a basis for accounting processes. Accounting processes consist of three phases, or (1) data inputs, (2) processing, and (3) outputs, and these are phases that are almost the same for all business activities. The accounting structure includes traditional and modern division. The basic financial statements (Statement of financial position, Income statement, Statement of comprehensive income, Statement of cash flows, Statement of changes in equity, Notes to the financial statements) are an important source of information on the business entity primarily for external users. The specifics of accounting for service companies of business entities define the specifics of monitoring revenues, expenses, costs and calculations in relation to other activities. The accounting regulations of the service activities of the Republic of Croatia relate to the accounting principles included in the accounting standards, the Accounting Act and other legal regulations of the service profession (Services Act). The accounting of the service activity on the example of the business entity Illaria JDOO presents the theoretical accounting regulation basis, and gives actual example and specifics of service activities through postings, financial reports and calculation.