A tax registration number is an identifier the government assigns so it can track your income and tax payments

A tax registration number (also called a tax ID or employer identification number) is a unique code issued by the tax authority in your country or state. In the United States, the Internal Revenue Service (IRS) assigns these numbers. The number lets the government match your income reports, tax filings, and payments to you specifically — whether you are a sole proprietor, a partnership, a corporation, or a nonprofit.

You need one if you are self-employed, run a business, hire employees, or operate as a nonprofit. Some people need one even if they do not have employees. The number itself does not mean you owe taxes or are under audit; it is simply a filing and tracking tool, like a social security number but for tax purposes.

Key Takeaways

  • A tax registration number is a unique identifier issued by the IRS (in the U.S.) or your state tax authority so the government can track your income and tax filings.
  • You need one if you are self-employed, operate a business, hire employees, or run a nonprofit organization.
  • The most common type is an Employer Identification Number (EIN), which is a nine-digit code formatted as XX-XXXXXXX.
  • You can request a tax registration number online, by mail, or by phone, and the process usually takes a few minutes to a few weeks depending on the method.
  • Having a tax registration number does not mean you owe taxes or are under investigation — it is a standard administrative requirement for most business structures.

Types of tax registration numbers and who needs them

The most common type in the United States is an Employer Identification Number (EIN). It is a nine-digit code formatted as XX-XXXXXXX. You need an EIN if you hire employees, operate as a corporation or partnership, run a nonprofit, or file certain tax forms. Even sole proprietors without employees sometimes need one — for instance, if you operate as an LLC or if you want to open a business bank account separate from your personal account.

If you are a sole proprietor with no employees and no business structure, you may be able to use your Social Security Number instead. However, many sole proprietors still obtain an EIN for privacy and to keep business and personal finances separate. Some states also issue their own tax registration numbers for state-level income tax or sales tax purposes; these are separate from the federal EIN.

Nonprofits, trusts, and certain other entities are required to have an EIN. If you are unsure whether you need one, the IRS website has a worksheet that walks through the decision based on your business structure and situation.

How to request a tax registration number

You can request an EIN through three main routes: online, by mail, or by phone. The online method is the fastest. You go to the IRS website, fill out Form SS-4 (Application for Employer Identification Number) in their online system, and receive your number immediately or within a few minutes. You do not need to print or mail anything.

If you apply by mail, you send a completed Form SS-4 to the IRS address listed on the form. Processing typically takes two to four weeks. By phone, you call the IRS Business and Specialty Tax Line, provide the information from Form SS-4 over the phone, and receive your number at the end of the call. Phone lines have specific hours and may have wait times, especially during tax season.

You will need basic information to complete the request: your name, address, the business name and address, the type of business structure, and the reason you need the number. If you are applying on behalf of a business, you may need to provide the name and Social Security Number of the owner or responsible party. No fee is charged for an EIN.

What information you provide when you request a number

Form SS-4 asks for your legal name, the business name (if different), your address, the business address, the type of entity (sole proprietor, partnership, corporation, nonprofit, etc.), and the principal business activity. You also state the reason you need the number — for example, "hiring employees," "opening a business bank account," or "filing a nonprofit tax return."

If you are applying as an individual, you provide your Social Security Number. If you are applying on behalf of a business entity, you provide the name and Social Security Number or EIN of the owner or responsible party. The IRS uses this information to set up the account and link it to your tax records. You do not need to provide income information, tax history, or financial statements at the time of request.

What happens after you receive your number

Once you have your tax registration number, you use it on all business tax forms, payroll documents, and filings. If you hire employees, you use it on W-2 forms and payroll tax returns. If you operate as a corporation or partnership, you use it on your annual business tax return. Nonprofits use it on Form 990 (the nonprofit tax return) and on grant applications.

The number itself does not trigger any automatic tax obligations. However, having a number means the IRS expects you to file the appropriate returns for your business structure. For example, if you have an EIN and hire employees, you are required to file payroll tax returns quarterly. If you operate as a corporation, you must file a corporate tax return annually. The specific obligations depend on your business structure and income level.

You should keep your tax registration number in a safe place and provide it to your accountant, bookkeeper, or tax preparer. You will also need it if you apply for business loans, open a business bank account, or apply for business licenses or permits.

Tax registration numbers and privacy

One reason many sole proprietors obtain an EIN even when not required is privacy. When you use your Social Security Number as your business tax ID, that number appears on tax forms and documents that may be seen by employees, contractors, clients, or financial institutions. Using an EIN instead keeps your Social Security Number off those documents.

An EIN is public information in the sense that the IRS can disclose it to authorized parties (such as creditors or government agencies), but it is not published in a public directory. Your Social Security Number, by contrast, is more sensitive and more frequently targeted for identity theft. Using an EIN for business purposes is a common privacy practice.

What a tax registration number does not do

Having a tax registration number does not mean you owe taxes, are under audit, or have done anything wrong. It is a neutral administrative tool. The number itself does not determine your tax liability — your income, deductions, and business structure do that. You could have an EIN and owe no taxes if your business has no income or if your deductions exceed your revenue.

A tax registration number also does not automatically register you with the state, obtain business licenses, or set up payroll. Those are separate steps. For example, you may need to register with your state's Department of Revenue for sales tax purposes, or obtain a local business license from your city. An EIN is federal and does not replace those state and local requirements.

Frequently Asked Questions

How long does it take to get a tax registration number?

Online requests are processed immediately or within a few minutes. Phone requests are completed during the call. Mail requests typically take two to four weeks. The timeline depends on the method you choose and the volume of requests the IRS is processing.

Can I use my Social Security Number instead of getting a tax registration number?

If you are a sole proprietor with no employees and no business structure, you can use your Social Security Number on your tax return. However, many sole proprietors obtain an EIN anyway for privacy and to keep business and personal finances separate. Some business structures (corporations, partnerships, nonprofits) require an EIN.

Do I need a separate tax registration number for each business I own?

Yes. Each separate business entity needs its own EIN. If you own two unrelated businesses, you request two separate numbers. If you own multiple locations of the same business under one legal entity, you use one EIN for all locations.

What if I lose my tax registration number?

You can look it up on previous tax returns, payroll documents, or business bank statements. If you cannot find it, you can contact the IRS directly or request a new one using the same process. The IRS will issue the same number if the business entity still exists.

Is there a cost to request a tax registration number?

No. The IRS does not charge a fee to request or obtain an EIN. Be cautious of third-party websites that charge fees to help you request one — you can do it yourself for free directly through the IRS.