Korea's tax office takes over the holding-tax choice that can cost a couple 5.28 million won

The choice comes down to 600 million won of assessed value. A couple that applies for the exemption deducts 1.2 billion won, as a sole owner does, and can then claim credits based on age and length of ownership ^[7]. A couple that does not apply forgoes those credits and takes two basic deductions of 900 million won, 1.8 billion won combined ^[8]. Applying therefore trades 600 million won of deduction for the credits ^[9].

Whether that trade pays depends on the two inputs to the credits. Couple A is 63 and has owned the home 12 years, and the exemption cuts the estimated bill from 2.178 million won to 1.93 million won, a saving of 248,000 won, or 11.4 percent ^[1][22]. Couple B is 49 and has owned theirs eight years, and applying would cost 5.279 million won against the 7.485 million won owed on separate assessment, 41.4 percent of the exemption bill ^[2][23]. B's swing is about 21 times the size of A's ^[20]. Set against B's 4.1 billion won assessment, it is 0.129 percent of the house ^[21].

Lim Kwang-hyun, commissioner of the National Tax Service, wrote on X on the 13th that "starting this year, the National Tax Service will for the first time calculate and notify married couples who jointly own a single home of the most advantageous comprehensive real estate holding tax," and that the agency "will also find and return the holding tax that people overpaid because they did not know" ^[10][11]. Lim said that "at the time of the regular November assessment, bills will be issued automatically at the most advantageous calculated amount" ^[5].

The choice exists because of two earlier repairs. A 2008 Constitutional Court ruling moved the holding tax from household to individual assessment, which left spouses paying on their own stakes and joint owners sometimes carrying more than sole owners ^[12]. In 2021 the government introduced the exemption, treating a jointly owned home as though one person held it ^[13]. It did not suit every couple, so the rules were revised to let each one choose ^[14].

Until this year the modelling was the taxpayer's job: log into Hometax, run the simulation and decide ^[15]. Lim said taxpayers "unfamiliar with tax law had to judge for themselves which option was better," and that older taxpayers in particular found the process burdensome ^[16]. In October 2024, as a member of the National Assembly, Lim was lead sponsor of a bill that would have required the agency to notify jointly titled single-home owners in advance of the better option ^[17].

In my view this is a live planning variable for expensive joint titles held by owners too young for the age credits, and administrative housekeeping for everyone else. The advantage swings with the home's price, the owners' ages and the holding period, and a couple who cannot decide in September still gets to pick the better method at the December return ^[25][18]. The counter-case sits in the agency's own screen: 8,600 taxpayers flagged in total, 5,700 of them people who never applied at all ^[19][3]. Lim did not give a won figure for either group ^[26]. If the typical mismatch looks more like A's 248,000 won than B's 5.279 million, the retrospective refund sweep is small money ^[1][2].