The engine answers only for a stated date and never defaults to today.
Covered? is it within the statute at all
Carved out? does an exception remove it
Judgment points the statute leaves open
Result
Answer for the payment in the case you have in mind.
What you’ve told it
Constitutional authority
This asks a different question than coverage: is the statute itself within the power the Constitution grants? The codified text can show what authority it rests on — but whether it stays inside that grant is a judgment the courts make.
Has a controlling authority determined whether 26 USC 3401 is within that power?