National Identification Number in the ESTA Application

When applying for ESTA to travel to the USA, you will be asked for your National Identity Number or National Identification Number. Learn what this means and what you can do if you don't have a National Identification Number.


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ESTA application: What is the National Identification Number?

For taxation, social benefits, and other government functions, many countries have assigned individual numbers to their citizens. These numbers have different names - depending on the country - and also look different from state to state.

The most common terms for national identification numbers are:

  • Personal Identification Number (e.g., Turkey)
  • National Identity Number (e.g., Norway, Albania)
  • National Insurance Number (e.g., United Kingdom)
  • NIN (e.g., Nigeria)
  • JMBG (e.g., Bosnia, Montenegro, and Croatia)
  • Social Insurance Number (e.g., Canada)
  • Social Security Number (e.g., USA)
  • Personal Identity Code (e.g., Finland)

In addition to general administrative procedures, the National Identification Number is also requested when applying for an ESTA permit for traveling to the USA.

National Identification Number for ESTA

Not everyone has a National Identification Number

In some countries, there is no National Identification Number. As a substitute, Tax Identification Numbers, Social Security Numbers, or even identity card numbers are used for various purposes.

Therefore, when filling out the ESTA application, many people without a National Identification Number wonder what should be entered in the fields "National Identification Number" and "Personal Identification Number."

ESTA application without National Identification Number

When filling out your ESTA application, the country of issuance of your passport will determine which numbers you need to include. For example, if you apply with a passport from Germany, Belgium, or the Netherlands, you will be asked to provide a National Identification Number.

The official ESTA page of the U.S. Customs and Border Protection states:

"Enter the number on your identity document, other than a passport, issued by your country. The National Identification Number, if issued to you, is required to complete the application."

So, if you do not have a National Identification Number, but the ESTA system asks you for one, you should enter the serial number of your ID card when filling out your ESTA application. You can find this in the machine-readable part of your ID document as well as in the upper right corner of the front.

Serial number on a German identity card

The National Identification Number is not requested in the official ESTA application if you fill out the form, e.g., with a passport from Austria, Switzerland, Poland, the United Kingdom, or Finland. In this case, it is sufficient to enter the passport number in the "Passport Number" field.

What is the Personal Identification Number?

In the official ESTA form, in addition to the fields "Passport Number" and "National Identification Number," there is also a field for the "Personal Identification Number." You do not have to fill in this field, and it is only clickable for you if you have a passport from a country with a Personal Identification Number.

Should I fill in UNKNOWN or not?

Some Internet guidebooks encourage you to enter the word UNKNOWN in the National Identification Number field if your country does not have an official National Identification Number. However, it is still requested in the ESTA application.

Based on official guidance from U.S. Customs and Border Protection, the USA experts at advise that you always use the serial number of your ID card instead of UNKNOWN. You should only answer UNKNOWN if you do not have a valid ID card.


If you need clarification on your ESTA application, you can use the ESTA Services of to prevent possible mistakes and resulting entry bans. With over 25 years of experience in all aspects of US visas, travel, and emigration to the USA, the government-licensed immigration consultants can reliably help you with all questions regarding your ESTA application.

US entry: Take your passport and ID card with you!

After you have entered both your passport number in the "Passport Number" field and the serial number of your ID card in the "National Identification Number" field in the ESTA application, you must carry both documents with you when you enter the USA.

This is so that US border officials do not doubt your identity when they compare the information in your ESTA with your passport documents.

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