Tax law is an area of legal study dealing with the statutory, regulatory, constitutional, and common-law rules that constitute the law applicable to taxation, which is the method by which the government levies on economic transactions. wikipedia.org

A subset of the field of commerce, business development comprises a number of techniques and responsibilities which aim at: wikipedia.org

Corporate law is the study of how shareholders, directors, employees, creditors, and other stakeholders such as consumers, the community and the environment interact with one another. wikipedia.org

International taxation is the study or determination of tax on a person or business subject to the tax laws of different countries or the international aspects of an individual country's tax laws. wikipedia.org

A consultant is a professional who provides professional or expert advice in a particular area such as management, accountancy, law, or any of many other specialized fields. wikipedia.org

Business analysis is the discipline of identifying business needs and determining solutions to business problems. Solutions often include a systems development component, but may also consist of process improvement, organizational change or strategic planning and policy development. wikipedia.org

"A business plan is a formal statement of a set of business goals, the reasons why they are believed attainable, and the plan for reaching those goals. It may also contain background information about the organization or team attempting to reach those goals." wikipedia.org

A business model describes the rationale of how an organization creates, delivers, and captures value (economic, social, or other forms of value). The process of business model construction is part of business strategy. wikipedia.org