Jennifer M. Kowal (Loyola-L.A.), Katherine Pratt (Loyola-L.A.) and I have posted Pursuing a Tax LLM Degree: Why and When? on SSRN.  Here is the abstract:

This Article and a related article, Pursuing a Tax LLM Degree: Where?, provide information and advice about Tax LLM programs to American law students and JD graduates who are thinking about pursuing a Tax LLM degree. This Article (1) discusses the costs and benefits of pursuing a Tax LLM degree, (2) explains the circumstances in which prospective Tax LLM students may be able to expand their employment options by pursuing a Tax LLM degree, and (3) compiles information and advice that tax law professors typically provide to prospective Tax LLM students in individual counseling sessions. This information includes a primer on tax practice employment opportunities, which vary based on (1) the nature of the work (i.e., transactional work or controversy work) (2) the type of tax subspecialty that is the focus of the tax practice and (3) the type of tax practice employer. The primer includes descriptions of various tax subspecialty areas, including business tax, international tax, estate planning, employee benefits, tax-exempt organizations, and tax controversies. This Article also offers advice to prospective Tax LLM students who are searching for tax positions with various types of employers, including (1) law firms (large, elite law firms, medium-size law firms, or smaller law firms), (2) accounting firms (Big Four accounting firms or smaller accounting firms), (3) the IRS, Treasury Department, or Department of Justice, (4) state taxing authorities, (5) corporations or other organizations, or (6) the U.S. Tax Court. For prospective Tax LLM students who hope to become full-time law professors, this Article also discusses the value of a Tax LLM degree in making the transition from tax practice to academia. In addition, this Article provides information regarding aspects of Tax LLM programs about which prospective Tax LLM students frequently inquire and addresses some common misconceptions about Tax LLM programs.