When a married couple owns a single home jointly, the default basic deduction for jongbuse (comprehensive real estate holding tax) is 900 million won each, 1.8 billion won combined. File a separate election and the couple is instead treated as a single-home household: the deduction drops to 1.2 billion won, but the age and long-term holding credits available only to sole owners open up. It is a trade — 600 million won of deduction surrendered in exchange for credits worth up to 80% of the assessed tax.
The filing window runs every year from 16 to 30 September. Which side wins depends on two variables, the government-assessed price of the home and the applicable credit rate, and in the calculation below the direction flips somewhere around 2.5 billion won.
What the 1.8 billion won deduction buys
As Seoul Shinmun sets it out, a couple owning one home jointly each deducts 900 million won of assessed value, 1.8 billion won combined. Electing the special treatment caps the combined deduction at 1.2 billion won while applying the age and long-term holding credits otherwise reserved for sole owners.
These are tax credits, subtracted directly from the calculated tax rather than from the tax base, which is why they move the final number so sharply. The National Tax Service publishes them along two axes, age and holding period; the two stack, subject to a combined ceiling of 80%.
| Age (as of the assessment date) | Age credit | Holding period | Long-term holding credit |
|---|---|---|---|
| 60 to under 65 | 20% | 5 to under 10 years | 20% |
| 65 to under 70 | 30% | 10 to under 15 years | 40% |
| 70 and over | 40% | 15 years or more | 50% |
Reaching the 80% ceiling takes a narrower set of combinations than it first appears. Age 70+ with 10 years held (40+40), age 65+ with 15 years held (30+50), and age 70+ with 15 years held (40+50, capped at 80) are the main routes. A 60-year-old who has held for 15 years still lands at 70%. Anyone in their early sixties or under ten years of ownership sits in the 40-60% band.
One further point: under the election, the spouse with the larger ownership share becomes the sole taxpayer — or, where shares are equal, whichever spouse the couple designates — and age and holding period are judged by that person. Designating the older spouse with the longer holding record is how the credit rate gets maximized.
At what assessed value does the election pay off
Here are both methods run on identical assumptions: a 50-50 ownership split; a tax base derived by subtracting the basic deduction from the assessed price and multiplying by the 60% fair market value ratio; and the residential rates published by the National Tax Service (0.5% up to 300 million won of tax base, 0.7% up to 600 million, 1.0% up to 1.2 billion). These are gross calculated amounts, excluding the property tax double-taxation adjustment and the rural special tax equal to 20% of the jongbuse.
| Assessed price | Joint ownership, standard (couple total, 10k won) | Election, 0% credit | Election, 40% credit | Election, 60% credit | Election, 80% credit |
|---|---|---|---|---|---|
| 2.0bn won | 60 | 276 | 165.6 | 110.4 | 55.2 |
| 2.5bn won | 210 | 540 | 324 | 216 | 108 |
| 3.0bn won | 384 | 840 | 504 | 336 | 168 |
Walking through the 2.0 billion won case: under standard joint treatment each spouse is treated as holding 1.0 billion won, so (1.0bn − 900m) × 60% = 60 million won is each spouse's tax base, and 0.5% of that is 300,000 won apiece, 600,000 won together. Under the election, (2.0bn − 1.2bn) × 60% = 480 million won becomes the base; 0.5% on the first 300 million is 1.5 million won, plus 0.7% on the remaining 180 million is 1.26 million won, for 2.76 million won. Only after an 80% credit does it fall to 552,000 won.
Two rules emerge. First, at an 80% credit rate the election wins at every price level — by a slim 48,000 won at 2.0 billion, but by 2.16 million won at 3.0 billion. Second, 60% is where the direction turns: at 2.0 billion the standard method wins (1.10 million vs 600,000), at 2.5 billion the two are effectively tied (2.16 million vs 2.10 million), and only at 3.0 billion does the election pull ahead (3.36 million vs 3.84 million). At a 40% credit or below, standard treatment wins across the board.
The election is not a tax break but an exchange. All that matters is whether the credit rate earns back the 600 million won of deduction it costs.
The pattern holds because the 600 million won gap between the two deductions is taxed at progressively higher marginal rates as prices rise, while the credit scales proportionally against that larger amount. Conversely, below 1.8 billion won of assessed value no tax arises under standard joint treatment at all, so the election never comes into question.
The exclusion filing for rental and employer-provided housing shares the same window but covers different ground; it is treated separately in a note on the exclusion filing deadline.
This year, missing the filing still gets you the better number
Something changed this year. According to Financial News, the NTS commissioner said the agency will calculate the most favorable amount for jointly-owning couples and notify each household individually, and will also seek out past cases where taxpayers overpaid because they were unaware of the election and refund them. Seoul Shinmun reported that filing or cancelling between the 16th and 30th of this month results in the November regular assessment automatically applying whichever calculation is more favorable.
The scale of the outreach was disclosed as well: roughly 5,700 households would benefit from filing the election, and roughly 2,900 existing filers would now be better off cancelling it. That second figure is the telling one. The election persists once filed, so a choice made years ago can turn unfavorable as assessed prices move and as age and holding period change.
No annual refiling is required as long as the marriage, the ownership shares, and other household members' home ownership stay unchanged. When something does change, a modification form goes in during the same window.
What to check
- Does the combined assessed price exceed 1.8 billion won — below that, standard joint treatment produces no tax and the election is moot
- Age and holding period of the designated taxpayer — add the 20-40% age credit to the 20-50% holding credit; below 60% combined, standard treatment wins across a wide range
- Prior filing history — if the election was filed years ago, rerun the numbers on today's conditions; 2,900 existing filers were identified as better off cancelling
- Changes in ownership shares — a gift or transfer that shifted the split triggers a modification filing
- Other household members' housing — if the single-home household requirement breaks, the election does not apply at all
- July and September property tax notices — the assessed price used for property tax is the starting point for the jongbuse base, so check it first
- The deadline — 30 September, filed with the district tax office or electronically via Hometax
Sources
- NTS to notify jointly-owning couples of the most favorable jongbuse, with refunds for past overpayments — Seoul Shinmun
- "Jointly-owning single-home couples will be notified in advance of the favorable calculation" — Financial News
- Comprehensive real estate holding tax rates — National Tax Service
- Tax credits for single-home households — National Tax Service