Korea's tax office computed the cheaper property tax option for 8,600 taxpayers

Choosing the special option costs a couple 600 million won of deduction. Apply for it, and this year's rules cut 1.2 billion won from the government-assessed value of the home, the same treatment a sole owner of a single home gets, and credits for age and length of ownership become available ^[7]. Decline it, and each spouse keeps a basic deduction of 900 million won, 1.8 billion won between them, with no credits at all ^[8]. So the question in each household is whether the age and ownership credits are worth more than the tax on that 600 million won of assessed value ^[3]. Lim Kwang-hyun, the commissioner of the National Tax Service, said the burden shifts with the price of the home and the owners' age and length of ownership ^[10].

Until this year the couple worked that out for itself, logging in to the Hometax portal, running the simulation and then applying or cancelling. Lim said the burden fell especially hard on older taxpayers ^[11]. In a Facebook post on the 13th, Lim said: "starting this year, the National Tax Service will for the first time calculate and inform married couples who jointly own a single home of the most favorable comprehensive real estate tax" ^[4][3].

"In this review, we found about 5,700 people for whom applying for the option is more favorable in tax terms, and about 2,900 existing applicants for whom canceling the option is more favorable," Lim said ^[12]. The two figures add to the roughly 8,600 taxpayers the agency says it will notify one by one, by mobile message or mail, with the estimated tax under the better method ^[1][13]. About 34 percent of the flagged set are people who had already found the option and filed for it ^[2], and the agency's own calculation says they should undo it.

On past years, Lim said: "The National Tax Service will look directly for people who paid more tax in the past because they did not know about the option or did not properly weigh which choice was better" ^[16]. The agency did not say how many overpayers it expects to find, how much it will pay back, or how many couples jointly own a single home ^[19].

Lim proposed this as legislation before he ran the agency. In October 2024, as a member of the National Assembly, he was the lead sponsor of a bill to amend the comprehensive real estate tax law. Under it, the National Tax Service would tell joint-owner couples in advance which option benefits them ^[17]. What the agency is doing now goes past advance notice, into refunds for years already paid ^[1].

The 8,600 is a count under this year's rules. If the tax revision bill clears the National Assembly, the basic deduction framework changes from next year, and Lim said that could change which choice is more advantageous ^[9]. A household told to apply in September could be told to cancel in the next cycle. The November notice also bills at the more favorable amount only for the taxpayers the agency flagged ^[14].

In my view the refunds matter more than the notices. A notice saves a couple one mistake this month; a refund the state initiates concedes that the office holding the assessed values and the ownership dates was always better placed to do the sum than the taxpayer was. The counter is that a set of 8,600 is small enough that the whole exercise costs the agency little more than a mailing run. "We will expand tailored guidance in areas where taxpayers find it hard to judge for themselves, reducing inconvenience and making sure they do not miss benefits they are entitled to," Lim said ^[18].