This article is written by a Japanese local.
For foreign professionals and entrepreneurs working in Japan, the annual “Tax Return (Kakutei Shinkoku)” held from February to March is one of the most complicated and unavoidable administrative procedures. Japan’s tax infrastructure relies heavily on paper-based workflows, which, combined with the language barrier, leaves many foreign employees feeling frustrated.
The key to eliminating this analog friction and smoothly completing your tax procedures from home with a single smartphone is the integration of Japan’s digital government infrastructure: the “MyNumber Card” and “e-Tax” (the Electronic Tax National Filing and Payment System).
This article provides an in-depth guide on the concrete requirements for foreigners to file a tax return in Japan using a smartphone and MyNumber Card, the system traps you are likely to encounter during the electronic application, and practical defensive measures to prevent errors.
1. The Logical Benefits of Using e-Tax for Expats
During tax season, the counters at Japanese tax offices (Zeimusho) get crowded, often resulting in hours of waiting. Furthermore, it is exceptionally rare for tax office staff to be capable of handling complex tax consultations in English or other languages.
By implementing smartphone filing (e-Tax) via your MyNumber Card, you can secure the following logical benefits:
- 100% Remote Completion: No need to visit a tax office; you can submit your return from home 24/7.
- No Physical Attachments Needed: In principle, you no longer need to mail or bring physical documents, such as your withholding tax slip (Gensen-choshu-hyo) or medical bills.
- Faster Refunds: Paper filings take 1 to 1.5 months to process a tax refund. With e-Tax, refunds are deposited into your designated bank account in roughly 2 to 3 weeks.
2. The “3 Essential Requirements” for Smartphone Tax Filing
To file your taxes electronically via e-Tax, the following infrastructure must be prepared in advance:
Requirement 1: A MyNumber Card with Valid “Digital Certificates”
Simply holding the plastic card is not enough. The “Digital Certificate for User Certification (4-digit PIN)” and the “Digital Certificate for Signature (6 to 16-digit alphanumeric password)” set during card issuance must be active. A frequent trouble occurs when an expat updates their Period of Stay (visa renewal) at immigration but forgets to separately update the expiration date of their MyNumber Card at the local city hall, causing the digital certificates to expire automatically.
Requirement 2: A Smartphone That Can Read the IC Chip
You need a smartphone equipped with NFC (Near Field Communication) capabilities. While iPhones (7 and later) and major Android devices work seamlessly, some niche phone models purchased overseas fail to physically read the IC chip of Japanese MyNumber Cards due to hardware compatibility errors.
Requirement 3: The “MynaPortal” App Installed
This is the mandatory bridge application required to connect the National Tax Agency’s filing portal with your MyNumber Card. Download it beforehand from the App Store or Google Play.
3. “System Traps” Faced by Foreigners and Defensive Measures
In practice, many foreign professionals experience errors during the initial setup that trigger security locks. Implement these defensive measures strictly:
Trap 1: Instant Lockout via Consecutive Password Errors
When reading the card with your smartphone, inputting the wrong password consecutively triggers an immediate lockout (3 errors for the 4-digit PIN, 5 errors for the 6–16 digit alphanumeric password). **Once locked, it is completely impossible to reset online; the user must physically visit their local ward or city office counter to submit an initialization request.** Getting locked out right before the filing deadline is fatal, so verify your passwords beforehand and type them carefully.
Trap 2: Character String Mismatch in Name Fields
If the alphabetical spelling of your name on your Residence Card, your bank account name, and your registered name on your MyNumber Card do not perfectly match in their character strings (e.g., presence of spaces, order of middle names), e-Tax will throw an error during initial user registration or when setting up your refund bank account. Entering the exact, identical text string across all systems is the only logic to prevent these errors.
Trap 3: Limitations of the English Interface
While the National Tax Agency’s filing system has gradually introduced English screens, not all tax deduction categories (such as medical expense deductions or foreign tax credits) are fully supported in the English environment. If filing a complex return, a realistic workaround is to use the Japanese screens alongside your browser’s translation functions (like Google Chrome translation) or seek assistance from your company’s HR department.
4. Q&A: Common Inquiries
Q. Do I need to report income earned overseas (e.g., rental income in my home country) on Japan’s e-Tax?
A. It depends on your “Tax Residency Status” under Japanese tax law. If you are a resident other than a non-permanent resident (generally meaning you have had a domicile or residence in Japan for more than 5 years within the last 10 years), your worldwide income is subject to Japanese taxation. Therefore, you are legally obligated to declare overseas income via e-Tax. Even “Non-Permanent Residents” (under 5 years of stay) may have to declare income remitted to Japan, so verify your physical financial facts carefully.
Q. How are my personal and tax data managed after completing the e-Tax filing?
A. You can review them anytime via your “MynaPortal” personal page. Past tax returns submitted through e-Tax, withholding data submitted by your employer, and records of income and resident taxes paid can be accessed, viewed, and downloaded as PDFs by logging into MynaPortal on your smartphone, mitigating the risk of losing paper copies.
5. Conclusion
Utilizing e-Tax with your MyNumber Card and smartphone is a powerful digital defense strategy to bypass Japan’s unaccommodating, analog tax workflows.
By applying front-loading—such as checking your card’s digital certificate validity after visa renewals and organizing your precise text strings—you can drastically reduce tax season stress. To ensure a smooth adaptation, HR managers should instruct foreign employees to verify their card’s digital certificates in January, well before the heavy congestion of tax season begins in February.