About twice a year, I get the same message from a tenant: their partner is moving in, or a friend needs a place to crash for a few months, and they want to know if that is okay. Over 15 years and 9 properties, I have learned that how you answer in the first 24 hours sets the tone for the next few years of that tenancy, so I never just say sure, go ahead.
A roommate request is really a request to change the contract, even if the tenant does not think of it that way. I treat it as a small screening and paperwork process, not a favor, and that habit has saved me from at least 3 messy situations where an undocumented occupant became a legal headache when the original tenant moved out early.
Why I never let this slide as a verbal yes
ud83duded2 RECOMMENDED ON AMAZON US
Top Property Management Books
Build the knowledge base that separates professional landlords from amateur ones.
In Japan, most leases specify who is allowed to live in the unit, and an unauthorized second occupant can technically be treated as a breach of contract. But I am not interested in being the landlord who evicts someone over a technicality. My real concern is practical: if a roommate moves in without paperwork and something goes wrong, like a rent shortfall or damage, I have no direct relationship with that second person and no way to hold them accountable. I have had one case, about 6 years ago, where an unregistered roommate stayed for 14 months before the original tenant quietly moved out, leaving me negotiating a move-out with someone whose name was not even on the lease. It took roughly 2 months of back and forth negotiating deposits and final utility charges, all because nothing had been put in writing.
My first response to the request
ud83duded2 RECOMMENDED PRODUCTS
Landlord-Tenant Law Guides
Know exactly what you can and cannot do u2014 essential reading before any dispute.
Within a day, I reply with roughly the same message every time. I keep it friendly but specific, and I always ask for three things:
- Full legal name and date of birth of the incoming person
- Their current employer or income source, since I run a light income check for anyone contributing to rent
- Whether they will be a co-signer on the lease or just an occupant, which changes what documents I need
I explain that this is standard for all 9 of my properties, not a special hurdle for them. Framing it as routine, rather than suspicious, keeps the conversation cooperative instead of defensive.
Screening the new occupant
I do not run a full credit check the way I might for a brand-new applicant, since the existing tenant already has a track record with me. But I do ask for proof of income if the new person will be splitting the rent, and I look for at least a monthly income of around 3 times the per-person share of rent, the same rough guideline I use for original applicants. If the incoming roommate cannot show that, I usually still allow it, but I raise the security deposit by about 20,000 to 30,000 yen to cover the added risk, and I tell the tenant exactly why. I also ask whether the new occupant has any pets, since that changes the pet deposit calculation on about half of my units, and it is much easier to sort out before move-in day than after a dog is already living in a no-pets building.
Updating the paperwork
ud83duded2 RECOMMENDED PRODUCTS
Property Inspection Forms & Checklists
Document everything. A signed checklist at move-in prevents every deposit dispute.
Once I am comfortable with the new occupant, I do not just let it ride on a text message exchange. I use a short one-page addendum to the original lease that names the new occupant, states the effective date, and confirms the total monthly rent is unchanged unless we agreed otherwise. I keep this template on hand and just fill in the blanks, so turning it around takes me about 15 minutes. Both the original tenant and the new occupant sign it, and I keep a scanned copy along with the original contract. This single document is what protects me if there is ever a dispute about who is responsible for damage or unpaid rent.
When I say no or ask for changes
I have turned down maybe 2 or 3 of these requests over the years, almost always because the unit was not built for the added occupancy, not because of the person. A studio designed for one tenant, for example, has different fire safety and water usage assumptions than a two-person share house. In those cases, I explain the specific reason, usually tied to the size of the unit or the septic and water capacity, rather than giving a vague refusal. I have also asked for a modest rent increase, typically 5,000 to 8,000 yen a month, when a second full-time occupant will clearly increase utility and wear-and-tear costs, and tenants almost always accept this once I explain the reasoning. In one case, the tenant tried to argue that the second person would barely be home, but I still held the line, because water and trash collection fees in my area are billed per unit, not per resident count, and the difference shows up on my side regardless of how often the roommate is actually there.
What I tell new landlords
If you are managing your own units, do not treat a roommate request as an annoyance to brush off with a quick text. Build a simple process: a short intake message, a light income check if rent is being split, and a one-page lease addendum you can reuse every time. It takes less than half an hour per request once you have the template ready, and it means you always know exactly who is living in your property and who is legally responsible for it.
That is the approach I use across all 9 of my properties, and it has kept roommate situations from ever turning into a legal or financial surprise on my end.
Property Management Company Evaluation u2014 12-Point Checklist
Developed after switching management companies twice. Saves you from costly mistakes that took me years to learn.
ud83cudfe0 More from DIY Father
15 years of landlord experience u00b7 3 apartment buildings u00b7 DIY renovations that saved millions of yen. Browse all articles at diytosan.com
