Overseas Income and Japanese Mortgages: Documents and FX

This article is part of the Zagdim Japan property series. It covers the income documents, exchange-rate conversion and income stability questions that come up when you apply for a Japanese mortgage with income earned outside Japan. It is written for readers with income in Taiwan or Hong Kong who are considering a Japanese property purchase.

Among the sources checked, only one loan, offered in separate Taiwan and Hong Kong versions, states publicly that overseas income can be used, and there is no unified official rule. Whether income earned overseas counts, and how it is converted, is left to the handling financial institution under Flat 35, and most private banks do not publish it. Among the banks checked, only Tokyo Star Bank (東京スター銀行) states, for its non-resident loan, that it uses an official income certificate from Taiwan or Hong Kong, converted at the exchange rate at the time of application.

As of September 2026, Flat 35 determines annual income from official certificates issued in Japan for the previous year, and the income documents that the other banks checked publicly require are also Japanese tax and payroll documents. Tokyo Star Bank’s loan is a real estate investment loan, not an ordinary mortgage for a home you live in. Whether a loan is approved is decided by each institution’s screening.

Why Does Overseas Income Stall a Mortgage Application?

Because, apart from Tokyo Star Bank’s non-resident loan, the income documents that Flat 35 and the banks checked publicly require are Japanese documents. Flat 35 (フラット35) is a long-term fixed-rate mortgage offered by the Japan Housing Finance Agency (住宅金融支援機構, an independent administrative agency) in cooperation with private lenders. You apply through a handling financial institution (取扱金融機関, a bank or similar lender that accepts Flat 35 applications). When income is determined, the basis is a certificate issued by a Japanese municipality or tax office. The documents listed by the banks checked include the withholding tax slip (源泉徴収票, the Japanese payroll withholding statement) and the final tax return (確定申告書, the document filed with the tax office to report income).

If your income is in Taiwan or Hong Kong, the documents proving it are local documents and are not on those lists. Official statistics do not cover this point either: the Ministry of Land, Infrastructure, Transport and Tourism’s survey of private mortgages, published in March 2026, does not list overseas income as a screening item.

If your income and your home are both overseas, you must also check the residence conditions, not just the income. For example, Rakuten Bank (楽天銀行, as of September 8, 2026) requires applicants to live in Japan and to have completed resident registration. The residence question is covered in the companion article “Can Foreigners Get a Mortgage in Japan?” in this series; this article deals only with income.

Which Income Documents Do Banks Publicly Require?

The table below lists the income documents publicly required in the sources checked. Each entry follows the institution’s own explanation, viewed at the end of September 2026. Bank conditions can change at any time, so rely on each bank’s latest notice.

Three points to note when reading this table:

• “Not stated” does not mean “not accepted”, and it does not mean “accepted”. These product descriptions do not say how income earned overseas is treated, so you can only confirm it with the bank.
• Tokyo Lucky Star says only “official proof of income”. The product description does not list which Taiwanese or Hong Kong document qualifies, so this must be confirmed with the bank.
• Flat 35 is handled differently from about January to May. During this period the previous year’s official certificate is not yet available, and how applications are handled at the time differs by financial institution.

Whether your income documents will be accepted depends on the source of your income, where you file taxes, and which product you apply for.

With Income in Taiwan or Hong Kong, How Does Tokyo Lucky Star Treat Income?

Tokyo Star Bank’s “Tokyo Lucky Star” is a real estate investment loan designed by the bank for people who do not live in Japan. Permitted uses include investment property, a second home and a home for family members, with a loan amount of 20 million yen or more and a variable interest rate. The two versions set different income requirements and cannot be applied to each other:

• Taiwan resident version (as of March 7, 2025): For holders of a Republic of China (Taiwan) passport who live in Taiwan, are Taiwan residents under the applicable tax law and are not residents of any other country or region, and who can submit an official proof of income. Prior-year annual income of 10 million yen or more, or net assets of 30 million yen or more; age 20 or over at application and 75 or under at full repayment; administrative fee of 0.1% of the loan amount (tax-exempt).
• Hong Kong resident version (as of April 1, 2025): For holders of a Hong Kong identity card whose main income is in Hong Kong and who can submit an official proof of income. Prior-year annual income of 15 million yen or more, or net assets of 45 million yen or more; age 65 or under at full repayment; administrative fee of 2.0% of the loan amount (tax-exempt).

In both versions, annual income and net assets are converted into yen at the rate the bank sets for the time of application, and in both you must be able to go to the bank’s head office to sign the contract. This has two implications. First, there is a net asset option in addition to annual income, so if your annual income falls short of the threshold, you can check whether your net assets meet it. Second, the Taiwan version requires that you be a Taiwan resident under tax law and not a resident of any other country or region; people who are also tax residents elsewhere do not meet this condition.

**Example: Mr. Chen, who lives in Taichung**

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Mr. Chen holds a Taiwan passport, lives in Taichung and works for a Taiwanese company, and is a Taiwan resident under Taiwan tax law. He wants to buy an apartment in Tokyo for his family to use when they visit Japan. He is not a permanent resident, so Flat 35 does not apply. Among the banks checked, the one that publicly accepts Taiwan residents is the Tokyo Lucky Star Taiwan resident version.

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He must prepare an official Taiwanese proof that shows his prior-year annual income. Whether his annual income reaches 10 million yen is determined by converting New Taiwan dollars into yen at the bank’s rate at the time of application. If it falls short, the bank then looks at whether his net assets reach 30 million yen.

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He must first confirm with the bank which Taiwanese document counts as an “official proof of income”, and he should watch the exchange rate used in the conversion. Whether a loan is approved is decided by the bank’s screening.

If You Are Posted Overseas or Have Just Returned to Japan, How Does Flat 35 Calculate Income?

This section applies only to Japanese nationals, permanent residents and special permanent residents, because Flat 35 accepts only these people (see the main article in this series).

• Applying while posted overseas: When applying for a home to live in, you must expect to return to Japan and be able to move in, and the handling financial institution must judge that confirming your intent for the contract and submitting documents pose no problem. How your annual income at the time of application is calculated must be discussed with the handling financial institution. If you are posted overseas after applying, the handling financial institution likewise decides.
• Applying after returning to work in Japan in the previous year: You can apply. Applicants with salary income only must ask their employer to issue a “document certifying income after returning to domestic work”.
• Applicants with income other than salary: Based on a copy of the previous year’s final tax return or similar, income earned while working in Japan is converted into a full year according to the number of days worked in Japan, and the result is treated as annual income (daily proration). For example, for an application in 2026, the period looked at is January to December 2025. A person who returns to work in Japan at some point between January and December 2026 cannot apply during 2026 and must apply from January 2027.

The timing of your return affects when you can apply and how annual income is calculated. The Flat 35 FAQ’s method is based on income earned while working in Japan. How income earned overseas during a posting is treated is not separately explained in the FAQ, and the answer of the handling financial institution governs.

If Your Income Is in a Foreign Currency, What Does the Exchange Rate Affect?

Exchange rates affect you at two points: the conversion of thresholds at screening, and later repayments.

• Threshold conversion: Only Tokyo Lucky Star publishes a conversion method, which uses the rate the bank sets for the time of application. The same annual income in New Taiwan dollars or Hong Kong dollars gives a different yen amount at different exchange rates, so for applicants whose income is close to the threshold, whether they qualify may depend on the exchange rate at the time of application. Flat 35 and the other banks checked do not publish a conversion method.
• Repayment: Tokyo Lucky Star loans are denominated in yen. If you repay a yen loan from New Taiwan dollar or Hong Kong dollar income, the yen amount due each period is calculated under the contract, while the amount you must pay when converted into New Taiwan or Hong Kong dollars moves with the exchange rate. This loan has a variable interest rate; how repayments adjust with interest rates follows the bank’s contract explanation.

How Do Banks Judge Income Stability?

The public sources show only a few general conditions, none of which addresses overseas income; for Tokyo Lucky Star, the only statement is that it judges on the annual income shown on the prior year’s official income certificate. In the ministry’s survey published in March 2026, of 994 financial institutions, 93.9% screen years of continuous employment (勤続年数) and 70.6% screen type of employment (雇用形態). These are shares of institutions that screen the item, not thresholds.

Two bank examples are published below, both assuming that you live in Japan. Bank conditions can change at any time; rely on each bank’s latest notice:

• SMBC Trust Bank: Its FAQ (updated October 3, 2025) lists prior-year annual income of 10 million yen or more and stable income; the FAQ does not explain how stability is judged. The bank’s application document table also lists, for people who have just changed jobs, an offer letter that confirms annual income.
• Tokyo Star Bank, Star Housing Loan (スター住宅ローン（永住権のない外国籍の方向け）, as of November 4, 2025): Applicants must prove through official documents that they have worked as a regular employee for 1 year or more, or have stable income for 3 or more periods as a company director or self-employed person.

For you, which year’s and which type of documents you can submit affects how your income is recognized. If you have just changed jobs, just returned to Japan, or are self-employed or a company owner, confirm the document types and the number of periods the bank requires before you apply.

Claims to Pause On and Check

• “Overseas income can be used for a Japanese mortgage” and “overseas income never counts”: The sources checked support neither claim. Only Tokyo Lucky Star publicly states an overseas income proof and a conversion method.
• “The Taiwan and Hong Kong versions have the same conditions”: The annual income and net asset thresholds, the age at full repayment and the administrative fees all differ.
• “Buying with Tokyo Lucky Star is the same as an ordinary mortgage”: It is a real estate investment loan with a variable interest rate, not an ordinary mortgage for a home you live in.
• “My credit record in Taiwan is good, so Japanese banks will take it into account”: No public mechanism could be found by which Japanese financial institutions query Taiwanese or Hong Kong credit records.
• “My income converts to just above the threshold, so I can borrow”: The conversion uses the exchange rate at the time of application, and meeting a threshold does not mean approval.

How to Decide Your Next Step

1. Where your income is recorded: in official certificates issued in Japan, or in official proofs of income from Taiwan or Hong Kong.
2. Where you live: in Japan or overseas. If overseas, first confirm the residence conditions.
3. The product you want to apply for, the date of its product description, and whether it states how overseas income and exchange rates are handled. If it does not, ask the bank directly.
4. If you are considering Tokyo Lucky Star, whether you fit the Taiwan version or the Hong Kong version, and whether your annual income or net assets reach the threshold after conversion at the rate at the time of application.
5. If you are a Japanese national or permanent resident who is posted overseas or has just returned to Japan, the timing of your return and when you can apply for Flat 35.
6. If you have just changed jobs, are self-employed or are a company owner, the document types and number of periods the bank requires.

To see the whole picture of status, interest rates and fees first, go back to the main article in this series, “Can Foreigners Get a Mortgage to Buy a Home in Japan?”

Overseas Income and Japanese Mortgages FAQ

I file taxes in Taiwan. Can my Taiwanese income proof be used to apply for a Japanese mortgage?

Among the sources checked, only the Tokyo Lucky Star Taiwan resident version states that it accepts an official Taiwanese proof of income, and it does not list which documents qualify, so you must confirm with the bank. What Flat 35 and the other banks checked publicly require are all Japanese tax and payroll documents.

Which day’s exchange rate is used to convert annual income into yen?

Only Tokyo Lucky Star publishes a conversion method: annual income and net assets are both converted into yen at the rate the bank sets for the time of application. Flat 35 and the other banks checked have not published a conversion method, so confirm with the institution you apply to.

When can I apply for Flat 35 after returning to Japan from overseas?

This applies only to Japanese nationals, permanent residents and similar. If you returned in the previous year, you can apply; applicants with salary income only must ask their employer for a certificate of income after returning. For applicants with income other than salary, for example someone who returned in 2026, applications start from January 2027.

Glossary

• Handling financial institution (取扱金融機関): A bank or similar lender that accepts Flat 35 applications.
• Official certificate (公的証明書): A certificate issued by a government body; for Flat 35, an income or tax payment certificate issued by a Japanese municipality or tax office.
• Withholding tax slip (源泉徴収票): Japan’s payroll withholding statement.
• Final tax return (確定申告書): The return filed with a Japanese tax office to report a year’s income.
• Tax certificate (課税証明書): A resident tax assessment certificate issued by a municipality.
• Years of continuous employment (勤続年数): The number of years of continuous service with the current employer.

Notes on the Data

• The information in this article was checked on September 30, 2026. It draws on the Flat 35 conditions and FAQ from the Japan Housing Finance Agency, the survey of private mortgages published in March 2026 by the Ministry of Land, Infrastructure, Transport and Tourism, and the product descriptions, FAQs and document lists that the banks published themselves.
• The following conclusions are drawn from documents and are not stated directly by any official source: “how Flat 35 treats income earned overseas, and what can substitute when no Japanese official certificate is available, has not been published by the official side” (checked against the Flat 35 conditions page and several FAQ entries, with no rule on overseas income or exchange rates found); “among the banks checked, only Tokyo Star Bank’s Tokyo Lucky Star states overseas income proof and exchange-rate conversion” (checked against the product descriptions or FAQs of MUFG, Sumitomo Mitsui, Mizuho, SMBC Trust, SBI Shinsei, Sumishin SBI, Rakuten, au Jibun, Sony and Suruga banks, and Tokyo Star Bank’s Star Housing Loan); “the ministry survey has no overseas income item” (checked against the full report and questionnaire); and “no public mechanism for querying Taiwanese or Hong Kong credit records could be found” (checked against the explanations of the three domestic credit information agencies).
• The sources checked contain no data on how much exchange-rate movements affect repayments, so this article makes no estimate; its statements about exchange rates explain only the principle of conversion.
• Bank information follows the dates given in the text. The two Tokyo Lucky Star product descriptions are the versions as of March 7, 2025 and April 1, 2025, and were still posted on the bank’s website at the check date. The number of periods of each document required in SMBC Trust Bank’s document table is not listed here. The Flat 35 post-return annual income calculation is explained in the FAQ using a 2026 application as the example.

Have a question about this guide? Leave a comment below, or ask Zagdim directly.

Sources

• Japan Housing Finance Agency – Flat 35 Conditions of Use (【フラット３５】ご利用条件)
• Japan Housing Finance Agency – FAQ Q&A394 「年収は何で確認すればいいですか。」
• Japan Housing Finance Agency – FAQ Q&A3266 「海外勤務中でも申込みできますか？」
• Japan Housing Finance Agency – FAQ Q&A3350 (申込後の海外転勤)
• Japan Housing Finance Agency – FAQ Q&A345 (給与収入のみ)
• Japan Housing Finance Agency – FAQ Q&A3332 (給与収入以外の収入がある場合)
• Ministry of Land, Infrastructure, Transport and Tourism – 令和７年度 民間住宅ローンの実態に関する調査 結果報告書（令和８年３月）
• Sumitomo Mitsui Banking Corporation – WEB申込専用住宅ローン 特設ページ
• SMBC Trust Bank – お申込時 必要書類一覧表（ローンマイページをご利用の場合）
• SMBC Trust Bank (Prestia) – よくあるご質問 No.144
• Tokyo Star Bank – スター住宅ローン（永住権のない外国籍の方向け）
• Tokyo Star Bank – 「東京招福星」スター不動産投資ローン（日本非居住者向け）商品説明書（台湾居住者向け）
• Tokyo Star Bank – 「東京招福星」スター不動産投資ローン（日本非居住者向け）商品説明書（香港居住者向け）
• Rakuten Bank – 楽天銀行住宅ローン（金利選択型）商品詳細説明書
• JICC – 他の信用情報機関との交流
• Japan Banks’ Personal Credit Information Center – 情報交流

Important Notice

This article is a general information summary. It is not individual advice on legal, tax or financial matters, and it does not represent any bank’s approval decision. The information was checked on September 30, 2026. Rules and bank products may change at any time; rely on the latest notices from the Japan Housing Finance Agency and the financial institutions concerned.