MyNumber in Japan: What Expats Need to Know for Banking and Taxes

Navigating Japan’s bureaucracy becomes significantly easier with the MyNumber card. We explain the difference between the notification slip and the plastic card, why banks and remittance services demand it, and how this ID is the key to seamless tax filing and convenience store administrative services.

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Why I Finally Stopped Ignoring That Green Envelope

When you first arrive in Japan, your mailbox is quickly flooded with envelopes. There are pension books, health insurance cards, bills, and flyers for sushi delivery. Among them, you likely received a nondescript green envelope that you might have tucked away in a drawer, thinking, “I will deal with this later.”

That envelope contained your “MyNumber” (Individual Number) notification. For a long time, many foreign residents, myself included, treated the MyNumber system as optional. We thought of it as just another layer of Japanese bureaucracy that we could politely ignore.

However, the landscape has changed. Today, living in Japan without a functional MyNumber card is becoming increasingly difficult. It is no longer just a tax ID; it is the golden key that unlocks digital banking, allows you to send money home to your parents, and saves you from taking mornings off work to visit the city hall.

In this guide, I will share everything I have learned about the MyNumber system. We will look at why your bank is asking for it, how it streamlines your tax returns, and why upgrading to the “plastic card” might be the best time-saving decision you make this year.

What Exactly Is the MyNumber System?

The “Social Security and Tax Number System,” commonly known as MyNumber, was introduced in 2016. In simple terms, it is a 12-digit identification number assigned to every person who has a registered address in Japan. This includes foreign residents.

If you are an American, think of it as a Social Security Number. If you are British, it is similar to a National Insurance number. The government uses this number to link your information across three main areas:

1. Social Security: Pensions, health insurance, and unemployment benefits.
2. Taxation: Income tax filings and local residence tax calculations.
3. Disaster Response: Tracking individuals during national emergencies.

Crucially, this number stays with you for your entire life in Japan. Even if you move from Tokyo to Osaka, or if you leave Japan and come back five years later, your MyNumber remains the same.

The Difference Between the “Paper” and the “Plastic”

This is the source of the most confusion for new expats. There are two “cards” associated with this system, and they serve very different purposes. Understanding the distinction is vital for your daily life.

1. The Notification Card (Paper)

When you first registered your address at the ward office, you were sent a green paper card (or more recently, a simpler notification letter).

• What it does: It simply tells you what your 12-digit number is.
• limitations: It is not a valid form of photo ID. You cannot use it to open a bank account online or prove your identity at the gym. In fact, the government has officially discontinued the “Notification Card,” meaning they are no longer re-issued if lost.

2. The Individual Number Card (Plastic)

This is the “real” MyNumber Card. It is a hard plastic card with an IC chip, your photo, and your address.

• What it does: It serves as official government ID, acts as your digital certificate for online taxes (e-Tax), and lets you print official documents at convenience stores.

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Comparison: Which Card Do You Have?

To help you clarify what is currently in your wallet, here is a breakdown of the differences.

Feature	Notification Letter/Card (Paper)	Individual Number Card (Plastic)
Material	Paper	Hard Plastic with IC Chip
Photo	No	Yes
Valid ID?	No (Verification only)	Yes (Official Photo ID)
Online Banking	Often Rejected	Accepted (e-KYC)
Konbini Printing	Impossible	Possible
Online Tax Filing	Limited	Full Access
Expiry Date	None	Tied to Visa Date (for expats)

Why Your Bank Teller Keeps Asking for It

You might have received a letter from your bank recently asking you to submit your MyNumber. Or perhaps you tried to open an investment account and were blocked until you provided it.

Since 2016, and increasingly strictly in recent years, Japanese law requires financial institutions to link bank accounts to MyNumbers. This is primarily for tax transparency. The government wants to ensure that interest income and overseas transfers are properly taxed.

If you ignore these requests, your bank may restrict your account functions. For investment accounts (like NISA or stock trading), providing a MyNumber is mandatory. You simply cannot invest in Japan without one.

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The Lifeline for International Remittances

For expats, the most critical function of MyNumber is sending money home. Whether you use Wise (formerly TransferWise), GoRemit, Seven Bank, or SBI Remit, you strictly need to provide your MyNumber.

Japanese anti-money laundering laws are extremely tough. Remittance services must report international transactions to the tax authorities.

The Scenario:

You want to send 100,000 yen to your family in your home country. You download a remittance app. The first thing the app asks for is “e-KYC” (Know Your Customer) verification.

• With the Plastic Card: You tap your card to your phone, scan the chip, and you are verified in minutes.
• Without the Card: You have to upload photos of your Juminhyo (Residence Certificate) which must contain the MyNumber, and then wait days for manual verification.

If you plan to support family abroad or pay student loans back home, getting the plastic card is essential for smooth transactions.

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Streamlining Your Taxes

If you are a regular salaried employee, your company likely asked for your MyNumber when you were hired. They need it to file your withholding tax slips and social insurance documents.

However, the real magic happens if you need to file a final tax return (Kakutei Shinkoku). This applies to freelancers, people with side hustles, or anyone claiming medical expense deductions.

e-Tax Revolution

Japan has a system called e-Tax for filing returns online. To use e-Tax securely, you need a digital signature. The plastic MyNumber card is that digital signature.

By using a card reader or a smartphone with NFC (Near Field Communication), you can file your taxes from your sofa. Without the card, you often have to print out paper forms and physically mail them or visit the crowded tax office in March.

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The Convenience Store Secret

This is my personal favorite feature, and the reason I recommend every expat get the card immediately.

In Japan, you often need official certificates for various life events.

• Juminhyo: To rent an apartment or buy a car.
• Inkan Shomeisho: To register a seal for a contract.
• Koseki Tohon: For marriage or family registry matters (mostly for Japanese nationals, but relevant if you marry one).

Traditionally, getting these meant taking a half-day off work, traveling to your local ward office (which is only open 9-5 on weekdays), waiting in line for an hour, and paying 300 or 400 yen.

The MyNumber Solution:

With the plastic MyNumber card, you can walk into almost any 7-Eleven, Lawson, or FamilyMart, 24 hours a day, 365 days a year. You go to the multi-copy machine, place your card on the reader, type in your 4-digit PIN, and print these official documents instantly.

Bonus: The fee at the convenience store is often cheaper (e.g., 200 yen instead of 300 yen) than at the city hall.

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How to Apply for the Plastic Card

If you only have the paper notification, upgrading to the plastic card is free. Here are the three ways to do it.

1. Smartphone Application (Easiest)

Your notification letter likely came with a QR code.

• Scan the QR code with your phone.
• It takes you to the application website.
• Take a selfie against a plain white wall.
• Fill in the form and hit submit.

2. Mail Application

Fill out the application form included with your notification letter, attach a passport-style ID photo, and mail it in the provided envelope.

3. Town Id Photo Booth

Some ID photo booths on the street have a MyNumber application function. You scan your QR code, pay for the photo, and the machine sends the data directly to the government.

The Wait Time

After you apply, it takes about 1 month for the card to be ready. You will receive a postcard in the mail saying your card is ready for pick up at your local city hall. You must go in person to collect it and set your passwords.

The Visa Expiration Trap

There is one specific headache that only foreign residents face.

For Japanese citizens, the MyNumber card is valid for 10 years.

For foreign residents, the MyNumber card expires on the same day as your visa (Period of Stay).

If your visa expires on July 1st, your MyNumber card also expires on July 1st.

When you go to immigration to renew your visa, you must also go to your city hall to update your MyNumber card.

The Critical Window:

You must update the card before it expires.

If you get your visa extended, take your new Residence Card to the city hall immediately. They will digitally update the chip in your MyNumber card and write the new expiry date on the front.

• Warning: If you let the date pass without updating it, the card becomes invalid. You will have to pay a fee (usually 1,000 yen) and apply for a brand new card, which takes another month.

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Security Concerns: Keeping It Safe

When the system first launched, there was a lot of fear about privacy. Japanese people are generally private about their personal data.

The Golden Rule of Safety:

The MyNumber card has your 12-digit number printed on the back. You should generally not show the back of the card to people.

• Front (Photo Side): Safe to show as ID at a bar, hotel, or gym.
• Back (Number Side): Only show this to your employer, bank, or government office.

Do not post photos of the back of your card on social media. The number alone can be used to attempt identity fraud, although the system has robust password protections.

The Future: Health Insurance and Driver’s Licenses

The Japanese government is aggressively pushing to integrate other IDs into the MyNumber card.

MyNa Hokensho (Health Insurance)

You can now register your MyNumber card to act as your Health Insurance card. This is called “Myna Hokensho.”

• Benefit: When you go to a hospital, you just scan your card. The doctor can (with your permission) see your medication history and checkup results, leading to better treatment.
• High-Cost Medical Expense: If you use the card, the system automatically calculates your monthly cap for expensive surgeries, saving you from applying for a separate “Limit Application Certificate.”

Driver’s Licenses

Plans are underway to integrate Japanese driver’s licenses into the MyNumber card chip in the near future. The goal is to have a single card for everything.

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Myna Points: The Government’s Reward System

To encourage people to get the card, the government runs campaigns called “Myna Points.” Although the major campaigns come and go, they are worth watching out for.

In previous campaigns, simply getting the card, linking it to a cashless payment app (like PayPay or Rakuten Pay), and linking it to your health insurance rewarded users with up to 20,000 yen worth of points.

For a family of four, that was 80,000 yen of free money. Always check if a campaign is active when you apply.

Lost Cards and Moving

If you move house:

You must bring your MyNumber card to the city hall of your new district when you register your new address. They will update the address on the chip. If you forget to do this within 14 days of moving, the card may become invalid.

If you lose the card:

1. Call the toll-free MyNumber support line immediately to suspend the card’s functions (available 24/7).
2. File a lost property report at the police station.
3. Take the police report number to your city hall to apply for a reissue.Note: You will have to pay a fee for a lost card replacement.

Conclusion: It Is Time to Get the Card

I resisted getting the plastic card for two years. I relied on my Juminhyo and my Residence Card. But the moment I needed to print a document on a Sunday night for a Monday morning apartment application, and I was able to do it at the 7-Eleven downstairs in 2 minutes, I was converted.

The MyNumber card is the cornerstone of Japan’s digital transformation. For expats, it simplifies banking, taxes, and daily administration. While the application process takes a little effort, the time you save over the next few years is immeasurable. Stop hiding that green envelope—scan the QR code and unlock the easier side of life in Japan.

Disclaimer

This article is for general informational purposes only and does not constitute professional advice. Laws, prices and regulations vary by location and change over time. Consult a qualified professional for guidance on your specific situation.