Your Korea Alien Registration Number: What the 13 Digits…

Thirteen digits. Everyone wants them.

You finally have your card. Then a shopping site rejects your number. A bank clerk asks you to confirm it again. After your visa change, you’re not even sure it’s the same number anymore. Every form in Korea wants it. Almost none of them explain it.

Your alien registration number (oegugin deungnok beonho) is the 13-digit ID printed on your ARC. Newer cards print “Residence Card” in English, but most people and most offices still say ARC. The number is issued by the Korea Immigration Service under the Ministry of Justice when you register your stay. If you haven’t registered yet, start with that process first.

This guide covers what the digits mean, where they trip people up, and how to get the number back when the card is gone.

What do the 13 digits on your card actually mean?

Your alien registration number follows a YYMMDD-GXXXXXX format. The first six digits are your date of birth. The seventh digit shows your sex and birth century, using 5 to 8 for foreigners instead of 1 to 4 for Korean citizens. The last six digits are administrative codes and a check digit. You never need to decode them yourself.

The 13-digit number structure meaning, digit by digit

Take a made-up example: 950312-5XXXXXX.

• 950312 = born on 12 March 1995
• 5 = male, born in the 1900s, registered as a foreigner
• XXXXXX = system codes plus a final check digit

The seventh digit is the one that matters most. Here’s the full pattern:

So a foreign student born in 2004 on a D-2 visa will usually have a number starting with 04, then a 7 or an 8 after the hyphen.

What about the last six digits? For Korean citizens, the Ministry of the Interior and Safety stopped using regional codes in that part of the number from October 2020. New numbers now carry random digits there. For foreign residents, the number is generated by the immigration system, not your local district office. Treat the back half as an identifier, not information. Anyone who claims they can read your hometown or visa type from it is guessing.

Here’s the catch. That seventh digit is also why some systems choke on your number. If the format matches a Korean number so closely, why do websites still treat you differently? That’s next.

ARC number vs resident registration number: same shape, different treatment

In law, the two numbers do the same job in most situations. Article 88-2 of the Immigration Act says alien registration substitutes for resident registration where other laws require it. Banks, NHIS, the National Tax Service and employers all accept your ARC number as your official ID number. The gaps appear in private websites, payment apps and older public systems.

The legal basis starts with registration itself. The Immigration Act, available in English through MOLEG, sets the rule:

“A foreigner who intends to stay in the Republic of Korea for more than 90 days from the date of entry shall register as a foreigner … within 90 days from the date of entry.” (Immigration Act, Article 31, English translation)

Once you register, your number becomes the key to almost every record you have. Here’s how it compares with the Korean resident registration number (jumin deungnok beonho):

Both numbers count as “unique identification information” under the Personal Information Protection Act. That means a company can’t freely collect and store your number without a legal reason. A shop asking for your full ARC number just to sign up for a loyalty card? You can say no.

One group works a little differently. Overseas Koreans on the F-4 visa have historically filed a domestic residence report (geoso singo) and received a separate card with its own number in the same 13-digit format. The rules for F-4 registration have been revised in recent years, so check HiKorea for which card applies to you before assuming anything. F-4 visa domestic residence report

So legally you’re covered. In practice, the trouble starts the moment you try to sign up for something online.

Why does a Korean website reject a perfectly valid ARC number?

Most rejections aren’t about the number itself. Korean sites usually confirm your identity through a mobile phone in your name, a joint certificate, or a bank-linked app. If your phone plan is under someone else’s name, or the form only accepts Korean numbers, verification fails even when your ARC number is correct. The fix is usually the phone line.

The three checks behind “using ARC number for online signup”

Korean sites rarely trust a typed number alone. They run identity verification (bonin injeung) through one of these:

1. Mobile phone verification. A code goes to a phone line registered with your name and ARC number, through SKT, KT, LG U+ or the PASS app. This is the most common method by far.
2. Joint certificate (gongdong injeungseo). A digital certificate issued through your Korean bank. Government sites like Government24 and Hometax accept it.
3. Private certificates. App-based certificates from Kakao, Naver, Toss and banks. Many sites now accept these too.

But it gets worse. If your phone is on a friend’s plan, a company plan, or some prepaid plans, mobile verification can fail every time. The number is fine. The phone just isn’t “yours” in the carrier’s database.

Steps that usually fix a rejected signup

1. Look for a foreigner (oegugin) tab or checkbox on the form. Many sites hide a separate path for foreign residents.
2. Type your name exactly as it appears on your card. Watch spacing and order of given name and surname.
3. Ask your carrier to confirm the line is registered to you with your current ARC number.
4. Ask the carrier to check how your name is stored. Long names can hit character limits, which creates a mismatch.
5. If a site still refuses, try a bank-linked certificate instead of phone verification.
6. For tax and public services, use a joint certificate on Hometax or Government24.

Getting a phone line in your own name solves most of these problems in one go.

Now the question people search right after a visa change. Did your number just change too?

Does your ARC number change after a status change?

Usually, no. When you change status, for example D-2 to D-10, D-10 to E-7, E-7 to F-2, or F-6 to F-5, the immigration office updates your record and prints a new card. The 13-digit number stays the same. The main exception is naturalization, because new Korean citizens receive a resident registration number instead.

When the number stays, and when it doesn’t

The number staying the same is good news. Your NHIS, bank and tax records don’t need a new ID. Most foreign residents are enrolled in the National Health Insurance Service after six months of stay, and that enrollment follows your ARC number through every status change.

What you still have to update

The number stays. Other details don’t. Under Article 35 of the Immigration Act, you must report changes to your name, sex, date of birth, nationality, or passport details within 15 days. Address changes have their own short deadline, so file within two weeks of moving to be safe. Late reports can lead to fines.

After a status change or extension, also update your bank. Many Korean banks track the stay expiry date on file and restrict accounts once that date passes. Bring your new card to the branch, even though the number is identical.

And if you re-register after time abroad, compare the number on your new card with your old documents. If it differs, update NHIS, your bank, your employer and your carrier right away.

Which leaves the worst case. What if the card itself disappears?

Lost your card? ARC number lookup if card lost

You can usually recover the number without the card. It appears on NHIS documents, bank account paperwork, your employment contract, payslips and year-end tax records on Hometax. For a replacement, apply for reissuance at your immigration office within 14 days of losing the card. Your 13-digit number stays the same on the new card.

Where your number is already written down

Check these before you panic:

• NHIS documents: your health insurance certificate or premium notices
• Bank paperwork: account opening forms or your banking app’s profile page
• Employment contract and payslips: E-7 and other workers usually have it on file with HR
• Tax records: withholding receipts on Hometax from the National Tax Service
• Phone contract: your carrier’s account records
• University records: D-2 and D-4 students can ask the international office

HiKorea’s online checks generally ask you to enter the number. They don’t retrieve it for you. If none of the above works, visit an immigration office with your passport. Officers can confirm your registration in person.

How to get a replacement card

1. Book a visit through HiKorea’s online reservation system.
2. Prepare your passport, one passport-size photo (3.5 cm x 4.5 cm), and the Integrated Application Form.
3. File a police loss report if the card was stolen. Some offices ask for it.
4. Pay the reissuance fee. Check the current amount on HiKorea before you go.
5. Collect the new card at the office or by mail, depending on what you choose.

Not sure which office covers your address? The 1345 Immigration Contact Center answers in multiple languages.

One more warning. A lost card is a fraud risk. Someone holding your number and photo could try to open a phone line or account in your name. Report the loss quickly. Don’t post photos of your card online, even blurred ones.

What should you do with your number this week?

Write your number in one secure place you can reach without the card. Confirm your phone line is registered to you. Check that your bank has your current stay expiry date. If you changed status recently, keep the old and new cards’ details side by side. Those four steps prevent most ARC number problems.

A short checklist:

• Save the number somewhere secure, like a password manager.
• Test one signup that uses phone verification. If it fails, fix the phone line now, not on deadline day.
• Update your bank after every extension or status change.
• Know your deadlines: 15 days for registration detail changes, about two weeks for an address move, 14 days to apply for a lost card.

Your number will follow you for years. A few minutes now saves a lot of trips to the immigration office later.