The Tax Foundation
The Tax Foundation is a nonpartisan organization founded in 1937. Its stated mission is to "educate taxpayers about sound tax policy and the size of the tax burden borne by Americans at all levels of government." The site offers podcasts, publications, data, charts, and maps.
Internal Revenue Service (IRS)
The Internal Revenue Service is the nation's tax collection agency and administers the Internal Revenue Code enacted by Congress.
Internal Revenue Bulletins (IRB)
The Internal Revenue Bulletin (IRB) is the authoritative instrument for announcing official rulings and procedures of the IRS and for publishing Treasury Decisions, Executive Orders, Tax Conventions, legislation, court decisions, and other items of general interest.
OECD’s annual statistical publication that presents a unique set of detailed and internationally comparable tax revenue data in a common format for all OECD countries from 1965 onwards.
StatistaThis link opens in a new windowIncludes a broad range of statistics from national and international data sources, searchable by industries, markets, topics, and countries.