To report an illegal apartment, contact your local code enforcement office (sometimes called the building inspection department, housing inspection division, or department of buildings) by phone, through an online complaint portal, or in person, and describe the unit’s address and the specific conditions you’ve observed. Most municipalities let you file anonymously or confidentially, and many larger cities route these calls through 311. A well-documented complaint moves faster than a vague one, so the work you do before you file matters as much as the filing itself.
Confirm the Unit Is Actually Unpermitted
Before you report, it helps to know whether the apartment is illegal on paper or just in poor condition. The two problems get handled differently.
The single most useful document is the certificate of occupancy. Issued by the local building department, it confirms a structure complies with building codes and lists the number of authorized dwelling units and the permitted use (residential, commercial, mixed-use). If your unit isn’t on that certificate, it was never approved for occupancy. You can usually request a copy from your city or county building department. Some municipalities have online property databases searchable by address; others require an in-person visit or a records request. Tenants and the general public generally have the right to obtain this document.
Zoning is the other piece. A property zoned for commercial or industrial use cannot legally house residential tenants without a variance or rezoning approval. Your municipality’s zoning map, usually posted on the planning department’s website, will tell you what uses are permitted at any given address.
Physical clues also point to unpermitted conversions, especially basements, garages, attics, and former commercial spaces. Common signs include escape windows too small to climb through, ceilings under seven feet in habitable rooms, makeshift walls that don’t reach the ceiling, extension cords doing the work of permanent wiring, and heat coming from space heaters or the kitchen stove rather than a permanent system. For units that were once legal but have slipped, look for broken smoke detectors, missing carbon monoxide alarms, unrepaired water damage, mold, pest infestations, plumbing that doesn’t work, and windows that won’t open.
Gather Evidence Before You File
Code enforcement officers respond faster to complaints they can act on. A report that something “seems off” can sit for weeks. A complaint with dated photographs, specific violations, and a clear description of the hazards gets prioritized.
Start with photographs and video. Document every visible violation: missing smoke detectors, exposed wiring, windows that don’t open or are too small, water damage, blocked exits, inadequate lighting, mold, and structural problems like cracked foundations or sagging ceilings. Photograph the exterior too, especially if the unit has a separate entrance that looks improvised, such as a new door cut into a foundation wall. Date-stamp everything.
Collect paperwork. Your lease, any written correspondence with the landlord about repairs, rent receipts, and records of previous complaints all help build a timeline. If you asked for repairs and were ignored, that pattern strengthens the case.
Statements from neighbors or other tenants add weight. Officers know a single complainant may have a personal grievance, but multiple independent reports of the same conditions are hard to dismiss. Formal affidavits aren’t required; a signed, dated letter describing what the person has seen is enough.
Where to File
Local code enforcement is the primary destination. The office name varies by municipality but the function is the same: it enforces building codes, zoning regulations, and property maintenance standards. If you don’t know where to start, call your city or county’s main line (311 in larger cities) and ask for code enforcement or housing inspection. You can also search the municipal website for “code complaint,” “building violation,” or “housing complaint.”
Other agencies handle overlapping problems. The local fire department or fire marshal responds to blocked exits, missing smoke detectors, overcrowding, exposed wiring, and locked emergency exits, and often moves faster than code enforcement on those. The health department handles sewage problems, lack of running water, serious pest infestations, and mold. For buildings in HUD-subsidized programs, you can file directly with HUD by emailing answers@hud.gov with “Rental Complaint” in the subject line, or by calling the National Multifamily Housing Clearinghouse at 1-800-685-8470.1U.S. Department of Housing and Urban Development. How Do I File a Complaint Related to a HUD-Subsidized Apartment
Anonymous vs. Confidential Reporting
Most code enforcement offices accept complaints without requiring you to identify yourself, but the distinction between anonymous and confidential matters. An anonymous complaint means the agency has no record of who filed it. A confidential complaint means the agency knows your identity but won’t disclose it to the landlord or the public without a court order. Some jurisdictions accept anonymous complaints only for emergencies that pose an immediate threat to life or safety, and reserve confidential status for less urgent reports.
Anonymous complaints sometimes receive lower priority, and the agency can’t reach you for follow-up questions or tell you the outcome. If you’re willing to provide your name confidentially, the investigation is usually more responsive. Tenants who live in the illegal unit face the trickiest situation, because a landlord can often figure out who complained regardless of confidentiality protections. Anti-retaliation laws exist for that reason.
What Happens After You File
Once the complaint is on file, the agency assigns an inspector to visit the property. Timelines vary. Some municipalities inspect within 48 hours for health and safety complaints; others take weeks for non-emergency issues. Ask for a case number when you file and reference it in every follow-up.
The inspector examines the property against local building codes and property maintenance standards. If violations are confirmed, the landlord typically receives a notice of violation listing each problem with a correction deadline, often 30 to 90 days depending on severity. Life-threatening conditions like no heat in winter, gas leaks, or structural collapse risk can trigger immediate condemnation orders that require tenants to vacate.
If the landlord misses the deadline, enforcement escalates. Many jurisdictions impose daily fines for ongoing violations, and cases can be referred for legal action. In some situations, the municipality will order the unit vacated and padlocked until the landlord brings it into compliance.
Your Rights If You Live in the Illegal Unit
Living in an illegal apartment doesn’t strip you of tenant protections. This is the single most important thing for tenants to understand, because landlords who operate illegal units often rely on tenants’ fear of eviction or deportation to keep them quiet. In most jurisdictions, you retain the same rights as tenants in legal units, and in some ways you may have more leverage.
The Landlord Can’t Just Push You Out
A landlord cannot lock you out, change the locks, or shut off utilities to force you to leave, even after the unit is found to be illegal. The formal eviction process still applies: written notice and, in most jurisdictions, a court order. Self-help evictions are illegal everywhere in the United States. If a landlord tries one, you can call the police and, in many jurisdictions, sue for damages.
Retaliation Is Prohibited
Every state has some form of anti-retaliation law protecting tenants who report code violations. These laws generally prohibit landlords from raising rent, reducing services, threatening eviction, or filing eviction proceedings in response to a tenant’s complaint. Some states presume retaliation if the landlord takes adverse action within a set period (often 60 to 180 days) after the complaint; others require the tenant to prove motive. Document any suspicious change in the landlord’s behavior after you report, and save all communications.
Rent Withholding and Ending the Lease
In many jurisdictions, tenants in uninhabitable apartments can withhold rent or terminate the lease without penalty. The legal basis is the implied warranty of habitability, recognized in nearly every state, which requires landlords to maintain rental housing in a condition fit for human occupancy. An illegal apartment that lacks proper exits, heating, plumbing, or ventilation almost certainly breaches that warranty. Some tenants use “repair and deduct” instead, paying for critical repairs themselves and subtracting the cost from rent. Rules differ by jurisdiction, so check local tenant law before withholding anything.
Recovering rent you’ve already paid is harder. Some courts have voided illegal-unit leases and ordered full refunds on unjust enrichment grounds; others have not. If you think you have a claim for past rent, consult a tenant rights attorney or your local legal aid office.
Relocation Assistance
If the apartment is condemned or ordered vacated, you may have to leave on short notice. A number of municipalities require landlords to pay relocation costs when a tenant is displaced through no fault of their own, particularly when the displacement follows code enforcement action. Amounts and eligibility rules vary. Ask your local housing agency or legal aid organization whether relocation assistance is available where you live and how to apply.
Reporting Unreported Rental Income
Landlords who operate illegal apartments often fail to report the rental income on their taxes. The IRS requires all rental income to be reported on Schedule E of Form 1040, whether or not the unit is legally permitted.2Internal Revenue Service. Renting Residential and Vacation Property If you believe your landlord is collecting rent off the books, IRS Form 3949-A is the standard route for reporting suspected tax law violations. The form asks for the taxpayer’s identifying information, the type of violation, and a description of the facts, and you mail it in.3Internal Revenue Service. Form 3949-A Filing 3949-A is voluntary and carries no reward.
For larger cases, the IRS Whistleblower Office offers awards of 15% to 30% of proceeds collected on qualifying information.4GovInfo. 26 USC 7623 – Expenses of Detection of Underpayments and Fraud The formal program has a high threshold: the taxpayer’s gross income must exceed $200,000 in the relevant year, and the total tax, penalties, and interest in dispute must exceed $2,000,000. Smaller cases may still receive a discretionary award, but the IRS is not required to pay one.5Internal Revenue Service. Whistleblower Office Most residential illegal-apartment situations won’t clear those thresholds, so Form 3949-A is usually the realistic option.