A company's outside accountant is an accountant who is not an employee of the company. An outside accountant could be a sole practitioner or a member of a firm that provides accounting services to many companies.
It is common for smaller businesses in the U.S. to utilize an outside accountant to assist in the preparation of the annual financial statements and tax reports. The outside accountant may also serve as a business advisor when needed.
Some outside accountants are certified public accountants while other outside accountants are not CPAs. Some of the outside accountants who are CPAs are not qualified to be independent auditors while others do qualify as independent auditors.
Since the outside accountant is not an employee of the client, the outside accountant will prepare an invoice in order to be paid for the services provided.