Ask Sam: I just found out my apartment is illegal. What should I do?

The best course of action will depend on in what way your apartment is illegal, says Sam Himmelstein, a lawyer who represents residential and commercial tenants and tenant associations. If the apartment is illegal in a way that constitutes a safety risk—such as an apartment that doesn't have appropriate fire egress, or a building with questionable structural integrity—it's possible that you'll need to move out ASAP.

"If the occupancy is dangerous and the building department comes around, they can slap a vacate order on it," says Himmelstein. "If there's a vacate order placed on it, there is very little that a tenant can do except get their stuff and get out as quickly as possible." Unfortunately, you can't necessarily recover the rent that you've already paid in this situation, unless you take your landlord to court on the grounds that your apartment was in violation of the Warranty of Habitability, and therefore the rent should have been abated.

If the apartment is illegal but not dangerous—maybe the landlord didn't properly amend the Certificate of Occupancy, or has added an illegal third apartment in a two family house,  or you're living          in a basement that's technically not supposed to be a bedroom—there are a few different ways things can play out.

"If the occupancy is illegal but not dangerous, then the buildings department might order the landlord to legalize the apartment or to get rid of it," says Himmelstein. It's also possible that you could legally withhold rent, since the Multiple Dwelling Law (which applies to buildings with three or more units) states that a tenant doesn't have to pay rent if the apartment isn't in conformance with the Certificate of Occupancy.

"You could withhold rent, and write a letter to the landlord saying that you've been made aware that the apartment you're living in is in violation of the Multiple Dwelling Law," says Himmelstein. "The landlord might say 'I don't agree' and sue, and then you'd end up in landlord/tenant court, which could land you on the tenant blacklist." On the flip side, if a judge rules in your favor, then you could be entitled to stay through the end of your lease rent-free.

In this case, however, if your landlord is embroiled in other legal issues that are a source of concern, says Himmelstein, "I would sit tight and see what happens next."

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Sam Himmelstein, Esq. represents NYC tenants and tenant associations in disputes over evictions, rent increases, rental conversions, rent stabilization law, lease buyouts, and many other issues. He is a partner at Himmelstein, McConnell, Gribben, Donoghue & Joseph in Manhattan. To submit a question for this column, click here. To ask about a legal consultation, email Sam or call (212) 349-3000.