From the article, here is the description of the current JCT and its role (footnotes omitted):
The JCT is a bipartisan committee of ten members of the House and Senate tax‐writing committees, and exists principally to provide justification for its staff. The committee does not report legislation, and rarely convenes hearings or performs other traditional functions of a legislative committee. The staff of the JCT — currently including about 50 economists, lawyers, and accountants — assists every member of Congress at each stage of the tax legislative process, and provides a source of tax expertise that is independent of the executive branch. The staff is nonpartisan rather than bipartisan; unlike staff supporting most other Congressional committees (including certain joint committees), the JCT staff is not affiliated with any party and is not separated into majority and minority party staff members.
Although the staff serves all of Congress, its principal duty is to be a policy advisor to the chairs, ranking members, and other members of the tax‐writing committees. In this role, the staff helps to develop, analyze, and evaluate many tax policy options for those committees and assists with all of the legislative tasks necessary for enactment of a bill. In addition, the staff provides the official revenue estimates used by Congress for all proposed tax legislation. The staff also reviews all tax refunds in excess of $2 million and monitors the administration of the tax laws by the IRS. Occasionally, the staff performs tax‐related investigations, such as examining President Nixon’s tax returns and the tax positions of the Enron Corp. The JCT and its chief of staff are given direct access to otherwise confidential tax return information and permitted to delegate that access to others.Here is the abstract of the article:
In early 1924, James Couzens was a Republican Senator from Michigan and reportedly the richest member of Congress. Andrew Mellon was beginning his fourth year as Secretary of the Treasury — a service that would eventually span 11 years under three Republican Administrations — and one of the wealthiest persons in the entire country. This article describes how a feud between these two men, an ensuing investigation led by Couzens of the Bureau of Internal Revenue (BIR) (predecessor to the modern-day IRS), and a tax case against Couzens that was described as the “greatest tax suit in the history of the world,” helped lead to creation of the U.S. Joint Committee on Taxation (JCT) and its staff. The events — filled with political intrigue, backstabbing (real or imagined), and unintended consequences — antagonized Congress’s relationship with the executive branch, but improved cooperation between the House and Senate, and both were instrumental in the JCT’s creation. The story also provides insight on the unique role the JCT has played in Congress for over 85 years. Finally, the article explains how creation of the JCT became entangled with two of the most contentious tax issues of the day — the publicity of tax return information and the depletion allowance for oil and gas production — and played a role in changing the law in both areas.The article also has some interesting history on the Sixteenth Amendment and the early income tax adopted pursuant to the ratification of the Sixteenth Amendment, including the following:
Although the income tax approved in 1913 was new, it had ample precedents. In drafting the initial bill for the House Ways & Means Committee, Congressman (and future Secretary of State under President Franklin Roosevelt) Cordell Hull (D.‐Tenn.) drew upon the experiences of the British income tax (over 100 years old), two earlier federal income taxes in the United States (one during and after the Civil War, and another briefly in 1894), and the country’s 1909 corporate excise tax that determined tax liability based on the amount of a corporation’s “net income.” To be sure, the final legislation was confusingly drafted and contained some gaping holes. For example, the statute appeared to permit deductions only for purposes of the normal tax, and not the surtax, thus raising the possibility that the law imposed, in part, a tax on gross income. Moreover, apart from drafting errors and ambiguity, there were embedded within the 1913 income tax law many difficult questions that required some compromise between the theory of an income tax and administrative considerations and other policy objectives. What the country needed was time to let the fledgling tax gradually mature. Unfortunately, world events soon made that hope an impossibility.There is a lot more history and intrigue. I strongly recommend the article.
For more reading, the web site for the JCT is here.