No deposit at all? what's the catch

It is genuinely zero in most cases, and your suspicion is reasonable but misplaced. Here is why the gap exists.

The deposit in a normal Korean rental is not a damage deposit. It is leverage. In the wolse system a large deposit lets the landlord lower your monthly rent — a 10,000,000 won deposit might mean 500,000 a month where a 3,000,000 deposit on the same room means 650,000. The landlord holds and invests your money; you get it back at the end. That system needs a big lump sum, a bank account and a contract.

A goshiwon does not run on that model. You pay month to month at a higher effective rate per square metre, and the operator makes money on volume and turnover instead. No lump sum needed, so none is asked for.

What you might actually pay beyond rent:

1. A key card or key deposit, 10,000 to 30,000 won, sometimes refunded when you return it.
2. A move-out cleaning fee at some buildings, typically 20,000 to 50,000 won. Not universal.
3. First month paid upfront, which is normal everywhere.

There is nothing to get back at the end because you did not put anything in. That is the trade — you keep your 5,000,000 won in your own account, and in exchange you have no equity in the arrangement and no protection beyond the month you have paid for.

The two things to actually verify before paying:

- Get a receipt or a KakaoTalk message confirming the amount, the period covered and the room number. A goshiwon usually has no formal contract, so this message is your entire paper trail.
- Pay to the business account, not to a personal account with an unrelated name. This is the one place where goshiwon payments do go wrong.

And ask for a 거주사실 확인서 (residence confirmation) when you move in — you will need it for your ARC, and it is easier to get on day one than a month later.