"The question is," said Humpty Dumpty, "which is to be master—that's all." With the IRS playing the lead role of Humpty Dumpty.

From An Empirical Study of Statutory Interpretation in Tax Law by Jonathan H. Choi. From the Abstract:

A substantial academic literature considers how agencies should interpret statutes. But few studies have considered how agencies actually do interpret statutes, and none has empirically compared the methodologies of agencies and courts in practice. This Article conducts such a comparison, using a newly created dataset of all Internal Revenue Service (IRS) publications ever released, along with an existing dataset of court decisions. It applies natural language processing, machine learning, and regression analysis to map methodological trends and to test whether particular authorities have developed unique cultures of statutory interpretation.

It finds that, over time, the IRS has increasingly made rules on normative policy grounds (like fairness and efficiency) rather than merely producing rules based on the “best reading” of the relevant statute (under any interpretive theory, like purposivism or textualism). Moreover, when the IRS does focus on the statute, it has grown much more purposivist over time. In contrast, the Tax Court has not grown more normative and has followed the same trend toward textualism as most other courts. But although the Tax Court has become more broadly textualist, it prioritizes different interpretive tools than other courts, like Chevron deference and holistic-textual canons of interpretation. This suggests that each authority adopts its own flavor of textualism or purposivism.

Remind you of someone? From Through the Looking Glass by Lewis Carroll.

"When I use a word," Humpty Dumpty said, in rather a scornful tone, "it means just what I choose it to mean—neither more nor less."
"The question is," said Alice, "whether you can make words mean so many different things."
"The question is," said Humpty Dumpty, "which is to be master—that's all."