Many U.S. citizens are surprised to learn that Japanese tax law treats U.S. income very differently from the U.S. tax system.
If you become a tax resident of Japan, your U.S. salary, investment income, retirement accounts, and remittances may all be taxed differently from what you expect.
Understanding these rules before moving to Japan can help you avoid unexpected tax liabilities and unnecessary mistakes.
Hello, my name is Taisei Koshida, and I am a certified public accountant and licensed tax accountant in Japan.
I specialize in assisting foreign business owners and individuals with Japanese tax compliance. Among my clients, U.S. citizens make up the largest group.
In my experience, almost every U.S. client is surprised when they first learn how their U.S. income is taxed in Japan.
In this article, I will explain how various types of U.S. income are generally treated under Japanese tax law, based on practical situations that I frequently encounter.
1. Resident Status for Japanese Tax Purposes
For Japanese tax purposes, many foreign nationals are treated as non-permanent residents during their first five years of residence in Japan, provided they do not have Japanese nationality and meet the relevant legal requirements.
This status is important because it affects how certain foreign-source income is taxed in Japan.
If you would like to learn more about non-permanent resident tax rules in Japan, this article may also be helpful.
Non-Permanent Resident Tax Rules in Japan: What Foreign Residents Should Know
2. How Foreign Income Is Taxed While You Are a Non-Permanent Resident
The easiest way to understand these rules is to separate income into two categories:
• Japanese-source income
• Foreign-source income
The tax treatment differs depending on which category the income belongs to.
(1) Japanese-Source Income
Japanese-source income is generally taxable in Japan.
Examples include:
• Salary earned from work performed in Japan
• Rental income from real estate located in Japan
• In many cases, capital gains from securities are also treated as Japanese-source income under Japanese tax law.
(2) Foreign-Source Income
Foreign-source income generally includes investment income earned outside Japan, such as:
• Dividends from U.S. companies
• Interest from U.S. bank accounts
• Rental income from U.S. real estate
• Distributions from Traditional IRAs, Roth IRAs, and 401(k) retirement accounts
If you are a non-permanent resident, this income is generally subject to Japan’s remittance-based taxation rules.
(3) Remittance-Based Taxation
One of the most common misunderstandings involves remittances.
Many people believe that remittance-based taxation applies only when they transfer foreign income to Japan. However, this is not how the rules work.
The source of the remitted funds does not matter. Even if you transfer money from savings accumulated before moving to Japan, it is still treated as a remittance.
Instead, the amount of foreign-source income taxable in Japan is generally limited to the lesser of:
• Your foreign-source income for the calendar year; or
• The total amount remitted to Japan during that calendar year.
For example, if you earn USD 1,000,000 of foreign-source income but make no remittances to Japan during the year, that income is generally not taxable under the remittance-based taxation rules.
On the other hand, if you remit USD 1,000,000 but have no foreign-source income during that year, the remittance itself does not create taxable income.
3. Traditional IRAs and Roth IRAs
One of the most common questions I receive from U.S. clients concerns the Japanese tax treatment of IRAs.
Under Japanese tax law, distributions from both Traditional IRAs and Roth IRAs are generally taxable.
However, when calculating taxable income, the cost basis may generally be deducted.
In addition, converting a Traditional IRA to a Roth IRA is generally treated as a taxable distribution under Japanese tax law because the assets are considered to have been distributed at their fair market value at the time of the conversion.
4. 401(k) Retirement Accounts
The same basic principles generally apply to 401(k) retirement accounts.
When distributions are received, the cost basis may generally be deducted when calculating taxable income.
Employer matching contributions may also form part of the cost basis, depending on the circumstances.
5. Calculating Capital Gains on Securities
Japan generally uses the moving-average method to calculate the cost basis of securities, whereas the United States often applies the FIFO method.
As a result, U.S. taxpayers who move to Japan should keep detailed records of each purchase and sale in Japanese yen.
Maintaining accurate records from the beginning can make future tax reporting much easier.
In my experience, reconstructing cost basis several years later can be extremely time-consuming. Keeping proper records from the beginning can save a considerable amount of time and effort.
6. U.S. LLC Income
The Japanese tax treatment of a U.S. LLC depends on its legal characteristics and how it is treated under Japanese tax law.
In many cases, if the LLC is regarded as a foreign corporation under Japanese tax law and has a management body, such as a board of managers or directors, compensation paid to a manager may generally be treated as foreign-source employment income.
Distributions from the LLC may also be treated as dividend income under Japanese tax law.
Because the tax treatment of U.S. LLCs can be complex, professional advice is often recommended.
If you would like to learn more about LLC taxation in Japan, this article may also be helpful.
7. Capital Gains on Securities
Under Japanese tax law, capital gains from securities are generally treated as Japanese-source income.
However, capital gains from securities that were acquired before becoming a tax resident of Japan may, in certain cases, be treated as foreign-source income.
This distinction can be particularly important for non-permanent residents because it may affect the application of Japan’s remittance-based taxation rules.
8. Conclusion
For many U.S. citizens moving to Japan, careful tax planning before relocation can significantly reduce future tax risks.
In particular, planning your remittances during your non-permanent resident period can make a substantial difference.
It is also important to maintain accurate records of securities, IRA contributions, Roth conversions, and 401(k) contributions so that taxable income can be calculated correctly under Japanese tax law.
In my experience, many tax issues can be avoided simply by planning before moving to Japan rather than after becoming a Japanese tax resident.
9. How Our Office Handles These Cases
When a new client contacts us, we first ask about their immigration history, Japanese tax residency, U.S. income, retirement accounts, investments, and remittance history.
Based on that information, we explain how Japanese tax law applies to their particular situation and suggest practical approaches before preparing any tax returns.
In my experience, discussing these issues before moving to Japan is usually much easier than trying to correct them after becoming a Japanese tax resident.
If you are planning to move to Japan, have questions about your U.S. income, or would like to discuss tax planning before relocating, please feel free to contact us through the inquiry form.
Early tax planning can often save a considerable amount of tax and prevent unnecessary complications later.
Tags: US Tax in Japan, Moving to Japan, US Citizens in Japan, Non-Permanent Resident Japan, Remittance-Based Taxation, Traditional IRA Japan, Roth IRA Japan, 401(k) Japan, U.S. LLC Japan, Japanese Tax Accountant