[formerkrogemp]

If the government asks if you, Bill the graffiti artist, painted any graffiti on the wall of a giant chicken, and you said no. They could still apply a penalty for lying to an LEO if that exists as a law if they can catch you later.

[doldols]

Of course, but the fifth amendment only protects you from self-incrimination if you explicitly invoke it (or keep your mouth shut). Not if you lie.

[saghm]

Does this mean you could fill in illegal income in your taxes and then for the source put down "I plead the 5th"?

[Bilal_io]

Then that would give them a reason to investigate.

They cannot ask you what you're pleading the 5th for, but they can go investigate it, and nail you when and if they find proof of illegal activity.

[dmurray]

What if everyone included "I plead the fifth" in their tax filings? Perhaps as a form of protest, or because CFAs and distributors of tax-filing software started adding it to their boilerplate?

[ThePowerOfFuet]

>and you said no

You're assuming you have to answer them; the 5th amendment allows you to refuse to respond in any way.

Refusing to respond isn't lying.