A lease deposit and the jeonse money of an obligatory jeonse automatically pass to the buyer regardless of registration. A deposit is basically money the tenant provides to the landlord on the condition that, when the tenant returns the leased property, the full deposit is returned if there has been no non-performance by the tenant, and if there has been non-performance, the balance after deducting the corresponding amount is returned. Therefore, the deposit secures the tenant's overdue rent and the tenant's obligations for damages due to loss of or damage to the leased property until the tenant returns it, and where the tenant has obligations between the expiry of the lease and the return of the leased property, they are naturally deducted from the deposit. In addition, where obligations for damages due to loss of or damage to the leased property already existed when the buyer acquired ownership, that amount of damages must also be deducted from the deposit. Once the leased house has been sold at auction after the tenant acquired opposability and the buyer has come to bear the obligation to return the lease deposit, the buyer's obligation does not disappear even if the tenant later moves their resident registration elsewhere, so the tenant can claim return of the lease deposit from the buyer.

Shin Bong-Geun, "Trends in Case Law under the Housing Lease Protection Act regarding Real Estate Auctions," Real Estate Auction Studies 2.2 (2021): 83-105.

Under the Housing Lease Protection Act, a lease acquires opposability when the tenant has completed delivery of the house and resident registration. In this regard, where two or more people conclude a housing lease contract as co-tenants and only one of them meets the requirements for opposability, the question is whether the other co-tenants cannot be protected. The Act has no provision on this. This can be said to be a question of whether opposability arises personally for the tenant or arises in rem and objectively for the lease relationship itself.

Since, by the wording of Article 3(1) of the Act, the subject for which opposability arises is stated to be the "lease," and since, in connection with delivery of the house, another requirement of opposability, each co-tenant must receive delivery of the entire house subject to the lease contract in order to meet the requirements for opposability even where each one's share of the lease is specified, opposability is regarded as arising for the lease relationship itself.

The co-tenants' claim against the landlord for return of the lease deposit cannot be regarded as an indivisible claim, but their claim against the landlord for delivery of the house appears to be an indivisible claim; in this respect, it appears that opposability of the lease arises for all co-tenants from the time any one of them completes resident registration and receives delivery of the entire house.

Park Tae-sin, "A Review of the Transfer of Leased Housing and the Right to Demand Renewal of a Lease Contract," Comparative Private Law 29.3 (2022): 1-21.

The Supreme Court clarified this legal principle and held that, if even one of the co-tenants of a house meets the requirements for opposability, that opposability extends to the entire lease contract, so when the leased building is transferred, the entire obligation to return the deposit to the co-tenants passes to the apartment transferee who succeeded to the landlord's position, and the transferor's obligation is extinguished. The same principle applies even where the co-tenants' shares of the lease deposit are set differently.

Even if the opposability obtained by one of the co-tenants extends to the entire lease, it cannot be said that third parties' rights are infringed in light of the purpose of public notice under the Act and transaction practice, and it appears sound in that the co-tenants can be protected.

The Supreme Court held that "if even one of the co-tenants of a house meets the requirements for opposability set out in Article 3(1) of the Housing Lease Protection Act, that opposability extends to the entire lease contract, so when the leased building is transferred, the entire obligation to return the deposit to the co-tenants passes to the apartment transferee who succeeded to the landlord's position, and the obligation of the transferor of the house is extinguished."

For reference, Article 3(3) of the Housing Lease Protection Act recognizes opposability for a corporation as well where a corporation that is a small or medium enterprise under the Framework Act on Small and Medium Enterprises leases a house for employee housing and an employee selected by the corporation completes delivery and resident registration. The corporation in this case was not treated as a case to which that provision applies, so the co-lease structure, in which it became a tenant together with the employee, became the issue. The citations of papers throughout the material's text are source attributions, so when using them in an assignment, check the judgment and each paper's original text directly. It is also good to note that the Supreme Court did not accept the lower court's indivisible-claim reasoning.