It's illegal to lie to the Federal Government period:

https://www.law.cornell.edu/uscode/text/18/1001

More precisely, it's a violation of 18 USC 1001 to lie about "any matter within the jurisdiction of the executive, legislative, or judicial branch of the Government of the United States" (with a couple of specific exceptions as given). Technically you don't even have to lie to a Federal official since the statute doesn't specify that; it just has to be a matter "within the jurisdiction" of the Federal government.