What to do when a tenant moves in an unauthorized occupant
If your tenant has moved in someone who is not on the lease, first confirm that the person actually lives there, then send a written notice that cites the lease, and offer a clean fix: apply and be screened as a tenant, or leave. Treat it like any lease violation, document every step, and do not set different rules for different people.
Is it a guest or a resident?
Guests visit. Residents live there. Your lease should say how many nights in a row or in a month make a guest a resident, and the guest policy guide shows how to write that. Without a rule, you are guessing.
Signs of a resident: their mail arrives there, their car is parked there every night, utility use jumps, neighbors report seeing them daily, or the tenant mentions them in a request. Do not spy. Look only at what you see in the normal course of managing the property.
What should I do before sending a notice?
- Reread the lease. Check the occupancy clause, the guest clause and the maximum number of occupants.
- Check the local occupancy limit. Fair housing rules protect families, so your limits must be reasonable and applied equally. Familial status is a protected class under the Fair Housing Act.
- Write down what you have seen, with dates.
- Ask the tenant directly and kindly. Sometimes the answer is a partner who just moved in and a ready willingness to apply.
What are the options?
| Option | How it works | Good when |
|---|---|---|
| Add the person to the lease | They apply, pass the same screening as any applicant, and sign an addendum. | You are happy with the person and the new rent split. |
| Approve as an occupant only | The person lives there, is named in an addendum, but is not responsible for rent. | A child or a dependent adult. |
| Send a notice to cure | Tenant must remove the person by a date or the notice moves toward the next step. | You do not want them there. |
| Do nothing | Not a real choice. If you ignore it, you may waive the rule. | Never. |
Whichever you choose, apply it the same way to every unit. If you treat some tenants differently with no clear reason, you open the door to a discrimination claim.
What goes in the written notice?
Name the lease clause, say plainly what you observed, state what must happen and by what date, and say what you will do if it does not. See what a notice to cure must contain. Most states set the form and the number of days for a notice, so use your state's rules. This is the common pattern, not legal advice. Rules differ by state and city, so check your state's law or ask a local landlord attorney before you act.
Example a made-up tenant's partner has stayed for about six weeks. The lease allows guests for 14 nights a month. You send a note quoting that clause, offer to screen the partner and add them by addendum, and give ten days to apply or move out. The partner applies, passes and signs, and the rent is split in the new lease.
Keeping it consistent
Consistency is your best protection, and it depends on records. DoorKeeping keeps the lease, any addendum and the message history in one tenant file, and lets leases and addenda be e-signed. You can ask Claude or ChatGPT to draft the note and to list which leases have an occupancy clause. You approve every message before it goes out.
Sources
- Fair Housing Act, 42 U.S.C. 3604 (Cornell Legal Information Institute), read Oct 30, 2026
- DoorKeeping: Connect Claude or ChatGPT (steps and tools list), read Oct 30, 2026
Questions
- Can I raise rent because another person moved in?
- Only if your lease allows it, or when the person is added in a new lease or addendum with agreed terms. Check your state before you charge more.
- Can I evict over an unauthorized occupant?
- It is a lease violation that can lead to eviction, but you generally must give a notice and a chance to fix it first, under your state's process.
- Does an occupant have to pass screening?
- If they will be a tenant who pays rent, screen them the same way you screen everyone. A minor child is usually not screened.
- What if the tenant says it is only a guest?
- Go back to your guest rule and the dates you recorded. A clear rule makes this conversation short.