Official letter from landlord for temporary stay? (permit related)

My bro recently signed a work contract in Zug, starting in September. In order to get the permit, he needs an apartment rental contract or "a place in which he will be officially living". I can host him for a couple months until he finds his own place, so I was thinking to ask my landlord (a big corp owning many apartments) for a letter, stating that he acknowledges/approves that my bro will be staying with me. I will be the one still paying the rent and everything (so it's not subrenting), so there's no change in the initial contract.

Is this the right way? A simple signed letter/email?

I’d do it by letter rather than e-mail and keep a copy for yourself just in case.

May depend on how big your place is and what it may say in your rental contract about the number of people that can live there.

I would think that the agency doesn't have a say in this, it's your decision. So any kind of proof/confirmation would have to be by you.

The first time I moved to Switzerland I lived with family friends. I believe they simply wrote an attestation that I was residing at their house, and that was sufficient to get a permit.

Even with subletting there will be no change in your contract.

But honestly, it might be best to make a written sublet contract With this it is known how much shall contribute (you can still waive it) and more importantly how you can kick out your brother.

Thanks everybody for the quick replies, we're trying the "a letter by you" and if that's not adequate, i'll ask the agency.

Would something as simple as the following be ok?

" I [my name], tenant of the apartment at [street], hereby confirm that [bro's name] will be staying in my apartment and this should be regarded as his official residential address in Switzerland until further notice. "

@Medea Fleecestealer: I couldn't find any clause in the contract limiting the number of tenants, but it might be in the small letters. Good point, thanks!

In a similar situation, in canton Zug, I made a subletting contract which was provided to the Gemeinde and I informed the agency, which said that it was fine for them.

I don't know if there are special regulations about this, but I thought that they do have a say. My rental contracts always stated the number of people living in, so changing that would be changing the contract - and I think the landlord has the right to disagree with that. Landlord agreed to rent you a space under certain conditions on how you will be using it, in the similar way they have a say on whether you can or can not have a dog or a cat in the apartment

Is the brother a (sub)renter though? I think he’s a guest. OP appears to concur, calls himself host.
Imagine his stay lasted two weeks, I figure that would be a clear case for a guest. I think the nature of the stay doesn’t change if it’s “a couple months”, the intended duration is short in both cases even if there’s no predefined end date.

Nonetheless it won’t hurt to have a written agreement. Not because of distrustm, quite the contrary, but to avoid problems and protect the relationship - “harte Geschäfte, gute Freunde”. Cleaning the bathroom, kitchen/ware, and apartment may be worth talking about, washing as well, mention that rent and other costs are zero. Who pays if stuff gets broken, keep in mind that the 3rd party liability insurance (do remember to take one) doesn’t pay for family members living in the same household. Perhaps also consider what’s mentioned in the template for subrent by the Mieterverband.

Quick update: it is stated after all in the initial contract (see attached photo) that an increase in the number of people living in the apartment (except for family growth) must be communicated to the landlord.

So, I emailed them, they sent me back a simple 1-page sublet form and all good. The form had a start & end date of the subletting, I left the end date open (no clue how long it will take for him to find a new apartment in the current situation), and they told me to let them know if he stays more than 6 months.