Which publication of the U.S. government, revised annually, is over 40,000 pages in over 20 volumes?

This colossal collection of rules and regulations is the United States Federal Tax Code. While the core law itself is known as Title 26 of the U.S. Code, the staggering page count often cited includes the vast body of accompanying IRS regulations, official rulings, and influential court decisions that interpret how the law is applied. Together, these documents create a dense and ever-expanding legal framework that governs every aspect of taxation.

The modern tax system began relatively simply with the passage of the 16th Amendment in 1913, when the entire law was only a few hundred pages long. Over the last century, it has ballooned in size as Congress has repeatedly used it for more than just raising revenue. Lawmakers constantly add deductions, credits, and complex rules to encourage or discourage specific economic and social behaviors, from buying electric cars to donating to charity.

This constant legislative tinkering means the code is revised annually, requiring a massive industry of accountants and lawyers just to navigate its intricacies. The result is a document that, by some estimates, contains millions of words—dwarfing the complete works of Shakespeare many times over and ensuring that tax season remains a challenge for almost everyone.