It would be an extreme if not an extravagant application of the Fifth Amendment to say that it authorized a man to refuse to state the amount of his income because it had been made in crime.

It is well-established federal law that the Fifth Amendment privilege does not extend to a taxpayer's failure to file any tax return at all

We can settle questions of that sort when an attempt to impose a tax upon a tax is undertaken, but not now.

—the Court held that the privilege against compulsory self-incrimination is not a defense to prosecution for failing to file a return at all.

—the Court held that a taxpayer was not privileged to refuse altogether to file an income tax return because part of his income derived from illegal activities.

"If the form of return provided called for answers that the defendant was privileged from making he could have raised the objection in the return, but could not on that account refuse to make any return at all."

We see no reason... why the fact that a business is unlawful should exempt it from paying the taxes that if lawful it would have to pay

It would be an extreme if not an extravagant application of the Fifth Amendment to say that it authorized a man to refuse to state the amount of his income because it had been made in crime. But if the defendant desired to test that or any other point he should have tested it in the return so that it could be passed upon. He could not draw a conjurer's circle around the …

The Court stated that the privilege could be sought against specific disclosures if the form of return furnished answers which the defendant was privileged from making and which he could have raised in the return, but the Court emphasized that this could not justify the refusal to make any return at all.

Apart from the context of the FLSA, case law is clear that employers are not excused from complying with federal laws, such as the FLSA, just because their business practices may violate federal law