If I tell a lie about my US citzenship (I am actually not), but not to a governmental agencies, I get no benefits, and I don't have the purpose to get any benefits from it, what code will specify the consequence? Am I removable?
To be more clear, is the sole action of lying illegal, or does lying must be accompanied with benefits in order to be deemed illegal. For example, in US I've heard that forging documents (such as ID) is not always illegal until you actually use them.
It's important to be clear about what you mean by "benefit," but if you're truly obtaining no legally cognizable benefit, then a lie about citizenship status is protected by the First Amendment. The government may not use it as the basis to take any action against you.
Under U.S. v. Alvarez, 567 U.S. 709 (2012), the fact that speech is false is not enough to allow the government to legislate against it. Instead:
The First Amendment requires that the Government’s chosen restriction on the speech at issue be “actually necessary” to achieve its interest. ... There must be a direct causal link between the restriction imposed and the injury to be prevented.
If the government were to try to punish the lie you're talking about, the courts would ask (1) whether there was a compelling governmental interest in restricting that speech, and (2) whether the government had found the narrowest way possible to do so.
In this case, the government would fail at step 1, and if it didn't, it would definitely fail at step 2.
Step 1: Lies about citizenship may have all sorts of consequences that the government has an interest in preventing (in the areas of employment, tax, and immigration, for instance), but it doesn't have any interest in prohibiting lies by which someone obtains no benefits whatsoever, and which therefore implicate none of those interests.
Step 2: If a court said that enforcing immigration or employment laws was a good reason to restrict lies about immigration, it would still find that the government had not found the narrowest possible way to enforce the speech restriction. In cases like this, courts routinely conclude that a law that punishes harmless speech in order to prevent harmful speech is not narrow enough, as the government can simply write the law to punish only the harmful speech.
So the lie would not affect a person's status. If they were not removable already, the lie would not make them removable. If they were removable, the lie would not make them any more or less removable.
Of course, all this assumes that you are not using too narrow a definition of "benefit," which the government would probably construe quite broadly. If you were not attempting to get a government benefit, but were trying to get a job or vote, for instance, either of those would be considered a "benefit" that the government of the type that the government would likely have an interest in regulating.
If you falsely claim to be a US citizen in order to obtain work, vote in a US election, or receive public benefits in the United States, you can be deported, lose a green card, or be banned from ever obtaining a green card or US Visa. See https://dyanwilliamslaw.com/2015/02/why-lying-about-being-a-u-s-citizen-can-stop-you-from-becoming-a-permanent-resident-and-what-you-can-do-to-overcome-this-obstacle/ and https://www.nolo.com/legal-encyclopedia/how-falsely-claiming-us-citizen-can-deportable.html for more detail.
This very much includes checking an incorrect box on an I-9 form when obtaining a job, although that is not usually considered a "benefit". In fact incorrect I-9 statements are a common source of such bans.
However, if a person lies in response to a merely curious question, when no government or private benefit, and no job eligibility is involved, the ban should not, as far as I can see, come into effect, nor should that be grounds for deportation, or indeed any criminal or immigration action.
If a person falsely claims to be a US Citizen merely to obtain social status or personal importance or reputation, that would seem not to be a crime under the doctrine of U.S. v. Alvarez, nor should it lead directly to any immigration consequences, althoguh I suppose it might draw attention to someone who is deportable on other grounds.
What code will specify the consequence?
8 USC 911, false personation of a US citizen.
As noted in other answers, the circumstances you describe suggest that free speech considerations would protect you from conviction.
am I removable?
Similarly, as noted in another answer, inadmissibility and deportability are triggered if the lie was for the purpose of obtaining a benefit under federal or state law. In the circumstances described, therefore, you would not be removable because of the claim of US citizenship.
