Calculating Comprehensive Real Estate Tax for Married Couples Under the 2026 Tax Reform Proposal

The comprehensive real estate holding tax on jointly owned homes can no longer be assessed with the simple statement that “joint ownership always saves taxes.” If the differentiated fair market value ratios and residence-linked deduction method proposed in the 2026 tax reform plan take effect, the more advantageous taxation method may vary depending on the officially assessed value, actual residence, age, and holding period.

This article analyzes the structure of the reform plan and simulations provided by the operator as of August 26, 2026. The tax reform plan is not itself finalized legislation, and its details, implementation timing, and calculation methods may change during revisions to the law and its Enforcement Decree.

Why Joint Ownership Does Not Automatically Qualify as One Household With One Home

Under the Comprehensive Real Estate Holding Tax Act, one household with one home generally means a household in which only one member owns a single home subject to property tax on housing. If spouses each own a share of one home, there are two persons subject to property tax, so they do not directly fall within this definition.

This does not mean that the couple is legally considered to “own multiple homes” even if they actually own only one home. More precisely, it means that they do not satisfy the standard requirements for classification as one household with one home under the comprehensive real estate holding tax. Everyday descriptions of the number of homes, tax rate application, and basic deduction classifications must be distinguished from one another.

Joint-owning spouses generally have two calculation methods.

The special provision for joint ownership does not change registered ownership to sole ownership. The ownership shares remain unchanged, while only the comprehensive real estate holding tax calculation method for the relevant year is applied differently.

Why Differentiated Fair Market Value Ratios Matter

In simplified terms, the comprehensive real estate holding tax base is calculated as follows.

(Total officially assessed value of homes owned - basic deduction) × fair market value ratio

The final tax is then calculated by applying the tax rates for each tax-base bracket, the deduction for overlapping property tax, the tax burden ceiling, and tax credits for seniors and long-term ownership. Therefore, if the fair market value ratio rises, the tax base may increase even when the officially assessed value and deduction remain the same.

According to the reform plan provided by the operator, the fair market value ratio would rise to 70% in 2027. From 2028, it would remain at 70% for sole owners qualifying as one household with one home in designated adjustment areas, while 80% would apply to other homeowners. If one jointly owned home is classified in principle under “other homeowners,” individual taxation may be affected by the higher ratio.

However, the fair market value ratio must be confirmed in the final legislation, including the Enforcement Decree. The geographic scope, applicable taxpayers, and implementation year must also be determined based on the final promulgated text.

Basic Deductions That Vary Depending on Actual Residence

The reform plan proposed raising the basic deduction for sole owners qualifying as one household with one home from KRW 1.2 billion to KRW 1.4 billion and applying the following formula to other homeowners.

KRW 400 million + KRW 500 million × proportion of the owner-occupied home’s value within the total value of all homes owned

Assuming this formula applies separately to each joint owner, whether the owners actually reside in the home can significantly change the result.

The table is a simplified comparison applying the reform plan’s formula to one home jointly owned 50-50. The actual calculation may be affected by whether other homes are owned, the ownership shares, the criteria for determining the owner-occupied home, and the method used to aggregate officially assessed values.

In particular, if the jointly owned home is leased under a jeonse or monthly rental arrangement while the couple lives elsewhere, the combined deduction under individual taxation could fall from KRW 1.8 billion to KRW 800 million. In this case, the decision should not be based solely on the existing explanation that “each joint owner receives a KRW 900 million deduction.”

The Special Provision May Be Disadvantageous Even at Lower Officially Assessed Values

The special provision for joint ownership is not subject only to a reversal in the high-value range. Individual taxation may also be more advantageous at lower officially assessed values.

Assuming spouses who jointly own a home 50-50 each receive a KRW 900 million deduction, no comprehensive real estate holding tax base may arise for a home with a total officially assessed value of up to KRW 1.8 billion. By contrast, if they elect the special provision and apply the KRW 1.4 billion basic deduction, a tax base arises for the portion of the officially assessed value exceeding KRW 1.4 billion.

The simulation provided by the operator presented the following results for a home with an officially assessed value of KRW 1.5 billion.

This example shows that even if the special provision provides tax credits, it may be less advantageous when the difference in the basic deduction is greater. The actual tax must be recalculated by applying the fair market value ratio, property tax deduction, and tax rates for the relevant year.

Reversal of Advantages Between Mid-Priced and High-Value Homes

The 2028 simulation included in the materials provided by the operator compared annual holding taxes combining the comprehensive real estate holding tax and property tax. Because it is not an official calculation table disclosing all specific tax rates and deduction conditions, it should be viewed as an example for understanding the structure rather than as an absolute benchmark.

Materials comparing only the comprehensive real estate holding tax indicated that the special provision was advantageous for officially assessed values between approximately KRW 1.9 billion and KRW 3.1 billion, while individual taxation resulted in a lower tax from approximately KRW 3.2 billion. The reversal point may differ when the comprehensive real estate holding tax and property tax are compared together.

The key factors behind this reversal are the basic deduction and the tax credit cap. The reform plan proposed limiting the combined tax credits for seniors and long-term ownership to KRW 8 million in 2027 and KRW 6 million from 2028. Even if the calculated tax increases as the home value rises, the relative advantage of the special provision decreases once the credit reaches the cap.

Accordingly, a particular officially assessed value should not be used as a fixed nationwide cutoff. The reversal range varies depending on ownership shares, age, holding period, actual residence, other homes, and the tax burden ceiling.

Taxation Methods to Compare First by Situation

Rather than choosing based on a single figure, such as “use the special provision if the officially assessed value is at most KRW 3 billion,” it is safer to calculate the estimated tax under both methods side by side using the same conditions.

Items to Check Before Calculating

1. Check the National Tax Service guidance for the tax base date for the relevant year and identify the owners of the homes and ownership shares as of that date.
2. Check the officially assessed value for the relevant year of the jointly owned home and any other homes owned.
3. Determine whether the spouses’ ownership shares are 50-50 or another ratio.
4. Confirm whether the home qualifies as the actual owner-occupied home.
5. Review each spouse’s ownership of other homes or shares in homes, as well as rights to move into or purchase newly built homes.
6. Check the age of the taxpayer under the special provision and the home holding period.
7. Apply the basic deduction and fair market value ratio applicable to individual taxation and the special provision, respectively.
8. Apply the tax credits for seniors and long-term ownership, the credit cap, the deduction for overlapping property tax, and the tax burden ceiling.
9. Choose the method after checking the final legislation and the National Tax Service guidance on filing for the special provision for the relevant year.

The officially assessed value and market value are not the same concept. Applying a fixed multiple to the officially assessed value to determine market value does not reflect differences among regions and homes, so the official assessed value should be used directly.

Filing for the Special Provision and Confirming Its Application

The filing period for the special provision for one jointly owned home has generally run from September 16 through September 30. However, whether the special provision applies in the following year and the procedures for changing or excluding its application must be confirmed in the National Tax Service guidance for the relevant year.

When considering a change in taxation method, the following should be checked in the National Tax Service guidance for the relevant year.

• Distinction between a new application for the special provision and a filing to exclude its application
• Which spouse will be designated as the taxpayer
• Joint ownership shares and the requirements for one household with one home
• Whether the provision automatically applies in the following year after an application
• Whether electronic filing through Hometax is available and which documents must be submitted

In the first year of the reform plan’s implementation, the treatment of existing applicants for the special provision or the procedure for excluding its application may also change. It is safer not to assume that the previous year’s method will automatically remain advantageous.

Why Ownership Should Not Be Changed Based Only on the Comprehensive Real Estate Holding Tax

Choosing a taxation method and changing registered ownership are entirely different decisions. Applying or declining to apply for the special provision for joint ownership means choosing how the comprehensive real estate holding tax is calculated, while transferring an ownership share to a spouse is an actual transfer of real estate ownership.

Changing ownership may involve the following costs and legal issues.

• Gift tax filing and application of deductions for a gift to a spouse
• Acquisition tax and local education tax on acquiring an ownership share
• Registration application costs and legal service fees
• Changes in the calculation of acquisition cost and holding period for future capital gains tax
• Mortgage agreement and financial institution consent issues
• Creditor relationships, composition of inherited property, and division of property upon divorce

Even if the annual difference in comprehensive real estate holding tax is several hundred thousand won or several million won, the cost of transferring ownership may be greater. Individual taxation and the special provision should be compared first, while a change in ownership should be considered separately only after calculating all tax and legal effects at the acquisition, holding, transfer, and inheritance stages.

The Reform Plan Must Be Distinguished From Finalized Tax Law

The announcement of a tax reform plan alone does not finalize the tax for the following year. Provisions established by law, such as the basic deduction, may require legislation by the National Assembly, while items prescribed by subordinate legislation, such as the fair market value ratio, require confirmation of amendments to the Enforcement Decree.

The following order is appropriate when making a final determination.

1. Confirm whether the amended law has passed the National Assembly.
2. Check the promulgation date and effective date of the law.
3. Check the final fair market value ratio under the Enforcement Decree of the Comprehensive Real Estate Holding Tax Act.
4. Check the National Tax Service filing guidance and calculation examples for the relevant year.
5. Verify that the home and ownership-share information in Hometax prefilled data and tax notices matches the actual registration records.

In conclusion, joint ownership itself does not automatically determine whether taxes will be lower or higher. Individual basic deductions may be more important in the lower price range, senior and long-term ownership credits in the middle range, and credit caps and the fair market value ratio in the higher price range.