On 19 December 2025, Japan’s ruling coalition published the 令和8年度税制改正大綱 (FY2026 Tax Reform Outline), confirming a structural change to how rental real estate is valued for inheritance purposes. The revision takes effect on 1 January 2027. For high-net-worth foreign nationals living in Tokyo or holding Japanese property, two overlapping rules now require attention: the long-standing 10-year residency threshold that determines global estate tax exposure, and the incoming five-year valuation rule that will significantly raise the 相続税評価額 (souzoku-zei hyouka-gaku, the assessed value used to calculate inheritance tax) on recently acquired rental properties. The window to act under the current, more favorable system closes on 31 December 2026.

The 10-Year Rule: What It Actually Governs

The phrase “Japan 10-year tax rule” circulates widely in English-language expat forums, but it is frequently misapplied. The rule does not concern capital gains on property sales. It governs whether a non-resident heir or gift recipient is liable for Japanese 相続税 (souzoku-zei, inheritance tax) and 贈与税 (zouyo-zei, gift tax) on worldwide assets or only on Japan-situs assets.

Under 相続税法 (Souzoku-Zei-Hou, the Inheritance Tax Act), specifically §1-3 and §1-4 as amended in 2017 and tightened again in April 2021, the rule operates as follows. A non-resident heir or donee who lived in Japan for more than 10 years within the 15 years immediately preceding the inheritance or gift is taxed on their global estate. A non-resident who does not meet that threshold is taxed only on assets physically located in Japan.

The practical consequence is significant. A foreign national who spent 11 years in Tokyo on a highly-skilled professional visa, then relocated to Singapore or London, does not immediately escape Japanese inheritance tax jurisdiction on assets held abroad. The 15-year look-back window keeps them within reach of the worldwide-asset rule for a period after departure.

The 2021 amendment introduced one important carve-out. Foreign nationals holding a Table 2 visa (特定活動, tokutei-katsudo, or certain employment-category residence statuses) are now excluded from the worldwide-asset rule even if they were resident for 10 or more of the preceding 15 years. However, 永住者 (eijuusha, permanent residents) and holders of Table 1 visas, including the highly-skilled professional visa (高度専門職, koudo-senmonshoku), remain fully exposed. If you hold 永住権 (eijuuken, Japanese permanent residency) and subsequently move abroad, the worldwide-asset exposure does not disappear on departure day.

For a detailed breakdown of how these residency thresholds interact with property ownership in specific wards, the Estate Tax in Japan: 2026 Rates, Residency Rules, and Property Implications for Foreign Owners guide covers the rate tables and residency scenarios in full.

The 2027 Reform: Rental Property Valuation Tightened

Separate from the 10-year residency rule, the FY2026 Tax Reform Outline introduces a structural change to the way 貸付用不動産 (kashitsuke-you-fudousan, rental real estate) is valued for inheritance and gift tax purposes. This is the reform most likely to affect HNW foreign buyers who have used Tokyo rental property as a wealth-transfer vehicle.

Under the current system, a ¥100 million rental マンション (manshon, Japanese usage: freehold condominium) in Minato-ku (港区) typically carries a 相続税評価額 of roughly ¥40 to ¥49 million. The gap exists because land is assessed at 路線価 (rosen-ka, the published road-frontage land price, approximately 80% of market), then reduced further as 貸家建付地 (kashiya-tatchi, land with a tenanted building on it), typically by an additional 20 to 30 percent. The building itself is assessed at 固定資産税評価額 (kotei-shisan-zei-hyouka-gaku, the fixed-asset tax assessed value, roughly 50 to 70 percent of replacement cost), then reduced again as 貸家 (kashiya, a tenanted building), typically by 30 percent. The combined effect produces a 50 to 60 percent discount to market value, which directly compresses the inheritance tax base.

From 1 January 2027, rental properties acquired within five years before the date of inheritance or gift will be assessed at acquisition price multiplied by 80 percent, adjusted for land price movements, rather than the current 路線価 and 固定資産税 basis. On a ¥100 million property, that shifts the assessed value from roughly ¥40 to ¥49 million to approximately ¥80 million. At a marginal inheritance tax rate of 30 percent, that single change adds ¥9 to ¥12 million in tax liability per ¥100 million of property, before any other adjustments. The FY2026 Tax Reform Proposals published by Japan’s Ministry of Finance sets out the broader reform context.

A second category is treated even more strictly. 不動産小口化商品 (fudousan-koguchi-ka-shouhin, fractional real estate products), including interests in 不動産特定共同事業 (fudousan-tokutei-kyoudou-jigyou, specified joint real estate ventures) and 信託受益権 (shintaku-jueki-ken, trust beneficiary rights), will be assessed at market transaction price regardless of how long they have been held. There is no five-year safe harbor for fractional structures.

What Is Exempt and What Remains Unresolved

Not all property is caught by the five-year rule. Self-use residential real estate, meaning property the owner occupies as their primary residence, is entirely unaffected. It continues to be assessed on the existing 路線価 and 固定資産税 basis. A ¥500 million owner-occupied house in Shirokane (白金) or Nishi-Azabu (西麻布) sees no change under this reform.

There is also a transitional carve-out for long-held land. Where the decedent or donor owned land for more than five years before the 通達改正日 (tsutatsu-kaisei-bi, the date the implementing ministerial notification is revised, expected in late 2026), and a new building was constructed on that land, the five-year clock on the building does not trigger the new rule, provided construction was complete or under way as of the notification revision date.

Several implementation details remain open as of April 2026. The 財産評価基本通達 (Zaisan-Hyouka-Kihon-Tsutatsu, the Basic Notification on Property Valuation) revision that will codify the exact methodology has not yet been published. Specialist tax firms have flagged at least five unresolved questions: how vacant units (空室, kuushitsu) will be classified; the precise methodology for adjusting acquisition price for land price movements; whether building values will be reduced by 定額法 (teigaku-hou, straight-line) depreciation from the acquisition date; how the new rule interacts with the 小規模宅地等の特例 (shougibo-takuchi-tou-no-tokurei, the Small-Scale Land Special Provision under 租税特別措置法 §69-4, which currently allows a 50 percent reduction on up to 200 square meters of rental land); and whether corporate ownership of rental property will face parallel restrictions.

Until the 通達 is published, precise tax modeling for any specific property is not possible. Buyers and their advisors should treat the numbers above as directional, not definitive.

The 2026 Transitional Window and the Anti-Avoidance Ceiling

Inheritances and gifts occurring on or before 31 December 2026 remain under the current favorable valuation system. A rental property acquired in 2026 and transferred by inheritance or gift in the same calendar year still benefits from the 路線価 basis. This makes 2026 the final year in which the legacy strategy of acquiring rental property to compress an inheritance tax base operates as it has for the past two decades.

However, practitioners are clear on one constraint. Even before 2027, the 財産評価基本通達6項 (clause 6 of the Basic Notification on Property Valuation) gives tax authorities an anti-avoidance override. The Supreme Court upheld the application of this clause in a landmark 2022 ruling involving a ¥13.8 billion apartment acquisition. Where a transaction is structured primarily to reduce inheritance tax with no substantive economic rationale, the National Tax Agency can disregard the 路線価 assessment and substitute market value. The 2026 window is real, but it is not a blank check.

For foreign buyers generating rental income from Tokyo property while navigating these inheritance rules, the Tokyo Rental Income Taxation for Foreigners: A Complete 2026 Guide covers the income tax side of the equation, including withholding obligations for non-residents and the interaction between rental income and residency classification.

At transactions of ¥300 million and above, the structural complexity of these overlapping rules is precisely where professional continuity matters. Koukyuu is a private buyer’s advisory where a licensed 宅建士 (takken-shi, Japan’s statutory real-estate transaction specialist) handles every stage of the engagement, from initial consultation through due diligence and contract signing. Most Tokyo agencies route clients through unlicensed salespeople until closing day. At Koukyuu, the same licensed specialist who advises on a property’s inheritance tax profile is the one who sits across the table at the 重要事項説明 (juuyou-jikou-setsumei, the statutory pre-contract disclosure meeting) and through to 登記 (touki, the transfer of legal title at the Legal Affairs Bureau).

Practical Implications by Buyer Profile

The two rules interact differently depending on a buyer’s residency status and intended use of the property.

Long-term foreign residents holding permanent residency. This group faces the broadest exposure. The 10-year worldwide-asset rule applies on departure, and any rental property acquired within five years of an inheritance event will be assessed under the new 2027 methodology. Estate planning that relies on Tokyo rental property to compress the taxable estate needs to be reviewed before 31 December 2026. Foreign nationals on work or investor visas, fewer than 10 years in Japan. Japanese inheritance tax applies only to Japan-situs assets. The 2027 rental property reform still affects the assessed value of those assets, but the worldwide-asset exposure does not apply. The calculus is narrower but the 2026 window is still relevant for anyone planning an intergenerational transfer of a Tokyo property. Non-residents acquiring Tokyo property as a pure investment. Rental income is subject to Japanese withholding tax at 20.42 percent on gross rents paid to non-residents, unless a tax treaty reduces that rate. Inheritance tax on Japan-situs assets applies at death regardless of residency. The 2027 valuation change will raise the assessed value of any rental property acquired within five years of the inheritance event, increasing the tax cost of passing that asset to heirs. All profiles. Fractional real estate products (小口化商品) are treated at market value from 1 January 2027 with no time-based exemption. Any holding in this category should be reviewed against the new methodology now, before the 通達 revision fixes the precise valuation mechanics. The Japan Real Estate Tax: Complete 2026 Guide for Foreign Buyers in Tokyo provides a broader map of acquisition, holding, and transfer taxes for non-citizen buyers.

Key Dates and Next Steps

The timeline is fixed on two ends and open in the middle. The FY2026 Tax Reform Outline was published on 19 December 2025. The new valuation rules take effect on 1 January 2027. The 財産評価基本通達 revision that will define the exact implementation mechanics is expected in late 2026, but no date has been confirmed as of April 2026.

For buyers and estate planners, the actionable dates are these. Any inheritance or gift completed by 31 December 2026 falls under the current rules. Any rental property acquired before the 通達改正日 on land owned for more than five years before that date may qualify for the transitional carve-out, subject to the construction timing conditions. Fractional product holdings have no transitional protection.

The National Tax Agency’s own guidance, including the Withholding Tax Guide for 2026, provides the statutory framework for withholding obligations that run parallel to these inheritance considerations. Cross-referencing both sets of rules is essential before any acquisition or transfer decision.

The practical recommendation for any HNW foreign buyer with existing or planned Tokyo rental holdings is to model the post-2027 assessed value of each property now, before the 通達 is published, using the acquisition-price-times-80-percent methodology as a conservative proxy. Then compare that figure against the current 路線価 assessment to quantify the increase in inheritance tax exposure. That gap, multiplied by the applicable marginal rate, is the cost of waiting past 31 December 2026.

Koukyuu is a private buyer’s advisory for distinguished Tokyo residences in Omotesando (表参道), Aoyama (青山), and Azabudai Hills (麻布台ヒルズ), focused exclusively on transactions of ¥300 million and above, with a licensed 宅建士 personally managing every stage from first consultation to title transfer. Book a private consultation) to discuss how these reforms apply to your specific situation.