Detailed instructions for registering an EIN number for a company established in the US (2026)

When a business starts operating or plans to expand into the US market, one of the first steps to take is to register for an EIN (Employer Identification Number), which is a business identification number issued by the US Internal Revenue Service (IRS).

The EIN consists of 9 digits, in the format XX-XXXXXXX, and is considered the “identity card” of a business in the US federal tax system. The US Internal Revenue Service (IRS) uses EIN to identify and track the tax obligations of organizations and individuals doing business, even when there are no employees.

Simply put, if you are a Vietnamese business opening a subsidiary, branch, or representative office in the US, an EIN is a mandatory condition to be able to:

• File and pay federal taxes for: corporate income tax, employment tax (FICA, FUTA), and excise tax.
• Opening a business bank account in the US: banks require an EIN to verify the legal entity and legal representative.
• Register business license, commercial contract or labor contract, pay employee salary.
• Report to the Social Security Administration (SSA) when paying employees.
• Conduct international or domestic financial transactions such as payments, profit transfers, or investments.

According to IRS guidance in Publication 1635, EINs are issued to many different types of legal entities, including:

• Sole Proprietorship.
• Corporation.
• Partnership.
• Limited Liability Company (LLC).
• Trusts, Estates, Exempt Organizations.
• And also other government agencies or specific organizations.

Each business should have only one EIN, corresponding to a separate legal entity. In the event that a business changes its organizational structure (e.g., from sole proprietorship to corporation), or merges to form a new legal entity, the Business must register for a new EIN.

EIN is used for business purposes only and is not a substitute for an individual’s Social Security Number (SSN). In addition, the Internal Revenue Service (IRS) recommends that no “nominee” should be used to register for an EIN, but that the legal representative, called the “Responsible Party,” who has actual control or management of the US business should be declared.

The EIN (Employer Identification Number) is issued and managed directly by the Internal Revenue Service (IRS), an agency of the US Treasury responsible for collecting taxes and enforcing federal tax laws. This is the only agency authorized to issue EINs to individuals, organizations or businesses doing business in the US.

According to guidance in IRS Publication 1635 – Understanding Your EIN, issuing an EIN helps tax authorities identify and track the tax obligations of each business unit within the entire system. 

When your business files a tax return, opens a bank account, or fulfills other financial obligations, the IRS uses the EIN to accurately identify tax records, avoiding duplicate or inaccurate information.

Businesses can apply for an EIN directly to the IRS through the following official channels: online application/fax/mail. 

EIN Registration Form (Form SS-4)

Since 2012, to ensure fairness and effective control, the IRS has limited the issuance of EINs to one per day per Responsible Party. This helps prevent duplicate registrations or misuse of EINs.

Illustration: 

A Vietnamese business opens an LLC in the US to do business through Amazon or use Stripe Payments for its e-commerce website.

When connecting a payment account, the Stripe/Amazon system requires an EIN to verify the business with the IRS. Without an EIN, the application will be rejected or payment capabilities will be limited.

Therefore, registering for an EIN is a mandatory step for businesses to be able to fully operate in the US financial and commercial system.

Below are important features of the EIN that businesses need to understand:

• The structure consists of 9 digits: EIN has the format XX-XXXXXXX, issued by the IRS (US Internal Revenue Service) according to a standard system across the whole federal. Each EIN is unique, associated with a specific legal entity.
• Each business has only one EIN: A business only needs to register for a new EIN when it changes its legal form (e.g., from Sole Proprietorship to Corporation).
• Sole Issuing Authority: Only the IRS has the authority to issue and administer EINs.
• Purpose: The EIN is used for business operations, taxes, and managing a business's financial records.
• Broad Scope of Application: EINs are issued to many different types of organizations, including corporations, partnerships, trusts, nonprofits, etc.
• Associated with the legal representative (Responsible Party): This person has the right to operate and control the business's operations and assets. IRS regulations do not allow authorization to a nominee (a person who stands in for the business).
• Not a substitute for a Social Security Number (SSN): An EIN is an identifier for an organization or business, while an SSN (Social Security Number) is for an individual. The IRS recommends not using an EIN in place of an SSN or vice versa.
• No Expiration Date: The EIN is valid forever, unless the business dissolves, ceases operations, or is revoked by the IRS for violations.

Any business that pays employees in the US is required to have an EIN to:

• Withholding and filing income tax for employees.
• Pay Social Security and Medicare taxes.
• Pay federal unemployment tax (FUTA).

For example: Your company hires employees to work in the US, even if there is only one employee, it needs an EIN to fulfill its employment tax obligations.

The following types of businesses are required to have an EIN, even if they have no employees:

• Corporations include both C-Corp and S-Corp.
• Limited liability company (LLC), whether single-member or multi-member.
• Partnership.
• Non-profit Organization.
• Trusts and Estates.

These legal entities are considered separate tax entities, so the Internal Revenue Service (IRS) requires each entity to have a separate EIN to file its respective tax returns and reports.

If you are a sole proprietor, you can use your SSN to file your taxes. However, you must apply for an EIN if you are one of the following:

• There are staff working.
• Open a corporate bank account.
• File federal tax returns (such as excise or employment taxes).
• Establish a pension fund, profit-sharing or savings plan for employees.
• Acquire or take over an existing business.

For foreign individuals or Vietnamese businessmen running companies in the US, EIN is also legal evidence to be recognized as a legal entity by banks and partners in the US.

Trusts, estates, or retirement plans, employee benefit plans (EINs) must register for an EIN to file tax returns independently, separate from the individual or business that manages them.

If you are required to pay or withhold excise tax, withholding tax, or other taxes imposed by the IRS, registering for an EIN is required to comply with your obligations and avoid administrative penalties.

The IRS requires businesses to determine their legal structure (business entity type) before applying for an EIN. This type affects how they file their taxes, their tax obligations, and whether they are assigned an EIN.

Some common types include:

• Sole Proprietorship (A private business owned by one individual).
• Partnership
• Corporation (C-Corp or S-Corp) (Joint Stock Company).
• Limited Liability Company (LLC) (Limited Liability Company with one or more members).
• Trust, Estate or Non-Profit Organization.

Note: Each type has different tax requirements, so determining the correct business type is the first and most important step.

The IRS only accepts EIN applications filed by Responsible Parties, that is, people who have direct control or operation of the business.

• For small businesses, this person is usually the owner or manager.
• For a large company or subsidiary, it may be the legal representative or the controlling shareholder.
• This person must provide his or her own valid SSN, ITIN, or EIN on Form SS-4.

The IRS does not accept a nominee or intermediary as the legal entity in a filing on behalf of a business.

Businesses need to fill in the information in Form SS-4 completely and accurately. Including:

• Legal Name and Trade Name (if any).
• Business address in the US (if applicable) or official contact address abroad.
• Date business started or acquired.
• Principal business activity.
• Estimated number of employees and first date wages paid.
• Reason for applying for an EIN (Reason for applying), e.g., starting a new business, hiring employees, opening a bank account, changing the type of business, etc.

Before applying for an EIN, businesses should have legal entity identification documents available to check with the IRS, such as:

• Certificate of Incorporation / Formation.
• Operating Agreement (for LLC).
• Articles of Organization / Articles of Incorporation.
• Business license (if any).
• Legal representative information and official contact address.

These documents do not need to be submitted directly to the IRS when applying for an EIN online, but should be kept on file for verification when requested by the IRS or when opening a US bank account.

The IRS allows businesses to register for an EIN in three ways:

• Online: Register directly at irs.gov.
• Fax: Send Form SS-4 to the IRS fax number.
• Mail: send hard copy documents to IRS address.

When a business changes its form of operation, resulting in a change in its legal nature, the Internal Revenue Service (IRS) requires a new EIN. Cases include:

• From sole proprietorship to corporation or partnership.
• From Partnership to LLC or Corporation.
• From a Single-Member LLC to a Multi-Member LLC, or vice versa.
• From Corporation to Sole Proprietorship after dissolution of the company.

As the type changes, the tax obligations, ownership structure, and legal status are different, so the IRS is required to issue a new EIN to ensure transparent tax tracking.

If the ownership or control of the business changes completely, for example:

• The business has a new owner due to purchase or transfer.
• The company is merged or acquired by another legal entity.
• The new shareholder or investor has absolute control.

→ At that time, the business must apply for a new EIN, because the IRS considers this a new legal entity, even though the name or business activities may remain the same.

• Two or more companies merge into a new company.
• A company split into several separate legal entities.
• The enterprise restructures its operating model to create a new independent legal entity.

In these cases, newly formed companies must register for a new EIN, while the old business's EIN can be closed or canceled after the final tax filing is completed.

If a business changes its legal representative or responsible party, a new EIN is not required, but notification to the IRS must be made within 60 days of the change.

Businesses use Form 8822-B (Change of Address or Responsible Party) to update information.

Note: If a business fails to update this information, the IRS may view the filing as invalid or delay processing future tax returns.

If a business only changes its business address or trade name (DBA), but maintains the same legal entity type, it does not need to apply for a new EIN.

However, businesses must notify changes in information to the IRS, banks, and relevant agencies to avoid errors when filing taxes or receiving letters from the IRS.

In case a business loses or does not remember the EIN it was issued, it does not need to reapply for a new EIN, but can contact the IRS directly to look up or request a reissued copy of the EIN Confirmation Letter (Form CP 575).

Note: If a business arbitrarily registers for a new EIN while the old EIN is still valid, the IRS may consider this a duplicate EIN registration, causing confusion in tax and accounting records.

An Employer Identification Number (EIN) is a 9-digit number issued by the Internal Revenue Service (IRS) to identify a business for tax purposes. The EIN functions similarly to a business's "identification card" in the US legal system.

Businesses need an EIN to open bank accounts, pay taxes, hire employees, sign contracts, and operate legally in the United States.

Yes. The IRS allows foreign businesses and individuals (Foreign Entities) to register for an EIN even if they do not have an SSN or ITIN.

In this case, the business needs to fill out Form SS-4, note “Foreign entity with no legal residence in the US” and submit the application via Fax or Mail to the IRS.

GLA prepares and submits this entire application on your behalf, helping you receive a valid EIN in just 4–6 business weeks.

Before applying, businesses need to prepare:

• Business type (LLC, Corporation, Partnership, etc.).
• Legal name and address of the company.
• Responsible Party Information.
• Reasons for applying for an EIN (opening a new company, opening a bank account, filing taxes, etc.).
• Certificate of Incorporation/Formation.

GLA helps you review all documents and fill out Form SS-4 correctly the first time. 

Businesses need to register a new EIN in the following cases:

• Change legal entity type (from LLC to Corporation, Partnership...).
• Transfer or change of ownership entirely.
• Merger, division or acquisition of a company.
• Establish a new legal entity in the US.

If you only change your address, business name, or representative, you do not need a new EIN, just update your information with the IRS.

You can fill out and submit Form SS-4 yourself if you understand IRS regulations. However, for international businesses without SSN, the Fax/Mail submission process is often complicated and can easily be rejected by the IRS if there is a small mistake.

GLA recommends using a professional consulting service to ensure that your application is valid, properly formatted, and processed as quickly as possible. Contact GLA for quick and efficient support in registering for a US company EIN. 

Once an EIN is issued, a business can:

• Open a corporate bank account in the US.
• Pay federal and state taxes.
• Register business license.
• Sign commercial contracts, hire employees, or conduct financial transactions.

GLA continues to accompany businesses after they have EIN, supporting account opening, tax consulting and completing legal documents for operations in the US.

Yes. Most US banks require businesses to have a valid EIN to open a business account. The EIN is proof of a business's legal status and financial integrity.

GLA provides full support, from registering for an EIN to opening a US bank account (Bank of America, Mercury, Wise, etc.), helping you complete the process quickly and legally.

No. An EIN is valid forever, unless the business is dissolved or revoked by the IRS for legal violations. Therefore, you can continue to use this number for the life of your US business.