Here, basic information refers to the most foundational elements of tax law, which are available through both subscriptions services and free-use websites.
Westlaw provides subscribers with administrative decisions and regulations regarding tax law. There is a federal tax link, which leads to the location of the Internal Revenue Code, Black's Law Dictionary, and federal tax cases. This is a very straightforward, helpful listing with much compiled into a small space.
Westlaw Tax Resources
LexisNexis subscribers also have access to tax administrative codes and regulations, as well as tax administrative materials, with a substantial collection of IRS documents and state-specific resources for your research needs.
LexisNexis Tax Law
Bloomberg Law includes a tax center that includes robust BNA portfolios for U.S. Income tax and a statutes and regulations sections featuring their collection of the IRS code and a substantial amassment of IRS agency documents.
Bloomberg Tax Center
Cornell University offers two important free-use services: WEX and the Legal Information Institute's collection of 26 USC (the federal tax code).
WEX is a free legal dictionary and encyclopedia, where tax law verbiage may be looked up, since it is a field where certain words may have their own specific meaning.
WEX Home Page
The U.S. Code for taxation is a list of all codified federal laws regarding taxes that an individual may look into to better understand their own or a client's financial situation.
The IRS also provides the Internal Revenue Code free of use so as to position taxpayers in a spot to access such pertinent information. The IRS actually links Cornell's Legal Information Institute compendium of the IRC, so it is seemingly the undisputed source for the code.
LII IRC Collection