Tax ID Number (The Ultimate Guide)

We’ve got the ultimate guide on tax ID number or TIN.

You have so many acronyms thrown at you and it’s confusing, EIN, SSN, ITN, ATIN, FEIN, PTIN, TIN…

What do these tax ID numbers represent?

What is an EIN?

What is the difference between EIN vs TIN?

What’s a PTIN?

The Internal Revenue Service or IRS uses different types of taxpayer-identification numbers to identify taxpayers in the United States.

In this article, we will break down the concept of taxpayer-identification numbers so you know all there is to know about it!

We’ll make your life easy, we’ll give you a simple description of what are the tax ID numbers used in the US, how to apply for one and what they mean.

We will also compare the different tax identification numbers like EIN vs TIN, EIN vs SSN, ITIN vs TIN and so on.

Are you ready!

Let’s get started!

Tax Identification Numbers

To start with, let’s look at the different types of tax ID numbers that may be issued to a person or a business:

  1. Employer Identification Number is known as “EIN
  2. Taxpayer Identification Number is known as “TIN
  3. Individual Taxpayer Identification Number is known as “ITIN
  4. Social Security Number is known as “SSN
  5. Adoption Taxpayer Identification Number is known as “ATIN
  6. Preparer Taxpayer Identification Number is known as “PTIN

Let’s look at each of them.

TIN (Tax Identification Number)

What is a TIN number?

A TIN or “Taxpayer Identification Number” is a type of tax ID number issued to a taxpayer for the proper administration of taxes.

TIN refers to a family of tax ID numbers and it is not a tax number itself.

The main purpose of a TIN is to ensure the right taxpayer is identified using a unique tax identifier.

A TIN can be assigned to: 

  1. Employers 
  2. Corporations
  3. Partnerships 
  4. Nonprofit associations
  5. Sole proprietorships 
  6. Trusts
  7. Estates 
  8. Government agencies
  9. Other businesses 
Tax Identification Number

Do you need a TIN number?

Yes, you need a TIN number whenever you correspond with the tax authorities.

Whether you are filing a tax return, providing documents, statements or other tax-related documents, you should make reference to your tax ID number.

By referring to a TIN, we are generally referring to a tax ID number.

As a result, when dealing with the IRS or the tax authorities, you must have some form of a tax identification number so they can trace your records and not of another taxpayer.

How do you get a TIN number?

When referring to a TIN, you are not referring to an exact or specific tax ID number.

As a result, without additional clarification as to what tax number is being targeted, it’s difficult to assess which tax number you are looking to get.

For example, generally speaking, TIN numbers are issued by either the Internal Revenue Services (IRS) while or the Social Security Administration (SSA).

Who issues Taxpayer Identification Numbers (TIN)?

Here is a simple chart outlining who issues Tax Identification Numbers:


EIN (Employer Identification Number)

What is an EIN number?

EIN or “Employer Identification Number” is a tax ID for businesses.

Estates and trusts will also get an Employer ID number if they have an income to report on Form 1041 US Income Tax Return For Estates and Trusts

EIN can also be referred to as “federal tax identification number”.

EIN is nine digits and acts as a unique ID number or reference number of a corporation, LLC or legal entity for tax purposes.

An EIN number is issued to:

  1. Employers 
  2. Corporations
  3. LLC companies 
  4. C Corporation
  5. S Corporation
  6. Partnerships 
  7. Nonprofit associations
  8. Sole proprietorships 
  9. Trusts
  10. Estates 
  11. Government agencies
  12. Other businesses 

The EIN number is formatted as follows: XX-XXXXXXX.

Do you need an EIN number?

You will need an EIN number if you answer “YES” to any of the following questions:

  1. Do you have employees?
  2. Do you operate a business such as a corporation or a partnership or other?
  3. Do you file employment tax returns?
  4. Do you file for excise, alcohol, tobacco or firearm tax returns?
  5. Do you withhold taxes on wages other than salaries paid to non-resident aliens?
  6. Do you have a Keogh plan?
  7. Are you involved with a trust (except certain grantor-owned revocable trusts), IRA, exempt organization business income tax returns?
  8. Are you involved with an estate?
  9. Are you involved with real estate mortgage investment conduits?
  10. Are you involved with non-profit organizations?
  11. Are you involved with farmers’ cooperatives?
  12. Are you a plan administrator?

How to apply for an EIN?

You can get an EIN number by applying directly with the IRS and meeting the necessary requirements. 

Let’s look at a few options.

Online application 

One easy option to apply and get an EIN number is to apply online for an EIN using the free service offered by the IRS to this effect.

As an individual, to apply online, you’ll need to already have an SSN or ITIN.

If you are a business, you must be a business entity with a legal residence in the United States or its territories. 

With an online application, your request may take a few days to complete at the most. 

Mail application

You can apply for an EIN number by sending your application forms completed originally by mail.

You’ll need the Application for Employer Identification Number (Form SS-4).

Those who do not have an SSN or ITIN number cannot apply online and must apply by mail, fax or phone.

You can look up the address of the IRS office for where you need to mail your application.

This process can be longer than an online application.

You should expect four to five weeks for the processing of your request.

Telephone application 

Another option offered by the IRS is to apply for an EIN number over the phone.

You can call the IRS at 267-941-1099.

To apply over the phone, your company must complete the Third Party Designee section of the Form SS-4 to authorize a specific individual to make the request.

Fax application

Although few people may be using fax these days, it’s worth noting that you can still send a request to the IRS to get an EIN number by fax.

You can visit the IRS website to ensure you are using the right fax number.

Puerto Rico applicants 

Employers in Puerto Rico must use the application Solicitud de Número de Identificación Patronal (Form SS-4PR).

ITIN (Individual Tax Identification Number)

What is an ITIN number?

ITIN or “Individual Tax Identification Number” is a tax ID for certain individuals such as:

  1. Certain nonresidents of the US and resident aliens
  2. Their spouses and dependents who do not have SSN

The individual tax ID number is assigned to a person required to pay taxes but who is not eligible to get a social security number or SSN.

An ITIN number acts as the physical person’s unique ID for tax purposes.

ITIN numbers begin with the number “9” and have 9 digits formatted in a similar way as a social security number (9XX-XX-XXXX).

How to apply for an ITIN?

You can obtain an ITIN number through the IRS by completing IRS Application for Individual Taxpayer Identification Number (Form W-7).

To get an ITIN number, you must establish:

  1. Your identity 
  2. Your alien status

Form W7 can be:

  1. Mailed 
  2. Delivered in person
  3. Submitted through an Acceptance Agent (colleges, financial institutions, accounting firms, law firm or other IRS-authorized organizations)

The Spanish version of Form W-7 is also available in Spanish speaking individuals.

The IRS offers an online interactive tool to help you determine if you should file an application to receive an ITIN number.

You can use the IRS’s Interactive Tax Assistance to verify your eligibility. 

SSN (Social Security Number)

What is an SSN number?

A social security number or SSN is a number issued by the Social Security Administration or SSA to:

  1. A US citizen
  2. A permanent resident of the United States
  3. A temporary nonimmigrant worker

The social security number is a unique numerical identification number to keep records of US individuals.

In other words, SSN is a person’s “national identification number”.

Social security numbers are composed of 9 digits formatted as follows: XXX-XX-XXXX.

Do you need an SSN number?

US citizens, permanent residents and temporary workers need a social security number.

SSN allows individuals to:

  1. File and report their taxes
  2. Get loans at the bank
  3. Get a US passport
  4. Get medicare 
  5. Register their automobile 
  6. Vote

For tax purposes, the IRS uses an US person’s SSN to properly administer an individual’s taxes.

How to apply for an SSN?

You can get a Social Security Number by filing the Application for Social Security Card (Form SS-5).

You can apply for an SSN online or submit the Form SS-5 in original at the nearest SSA office serving your area.

The SSN is issued by the Social Security Administration or SSA and not the IRS.

An applicant must present the following evidence in support of an SSN request:

  1. Proof of identity using a government-issued ID
  2. Proof of age
  3. Proof of US citizenship
  4. Proof of lawful alien status if applicable 

Non-Americans will need to apply for a social security number from within their home country at the Social Security Field Office.

ATIN (Adoption Taxpayer Identification Number)

What is an ATIN number?

ATIN or “Adoption Taxpayer Identification Number” is a temporary tax ID number issued to individuals who are in the process of adopting a U.S. citizen or a resident child but who cannot get an SSN for that child in time to file their income tax return.

How do you get an ATIN number?

You can get an ATIN number through the IRS by completing the Application for Taxpayer Identification Number for Pending U.S. Adoptions (Form W-7A).

PTIN (Preparer Tax Identification Number)

What is a PTIN number?

PTIN or “Preparer Tax Identification Number” is a tax ID number used by tax preparers.

A person preparing all or substantially all of a person’s federal tax return or claims a refund for another must have a PTIN.

If a person helps you prepare your income tax returns, it is mandatory that they indicate their PTIN number on your tax return documents.

How to apply for a PTIN?

A tax preparer can get a PTIN number by using the IRS sign-up system by filing an online application.

You can also apply for a PTIN using IRS Paid Preparer Tax Identification Number Application (Form W-12).

A foreign preparer without a social security number can look up the foreign preparer’s applicable IRS requirements

You can also fill out the Form W-12 and send it to the designated IRS center.

TIN Comparisons


EIN and TIN are both taxpayer-identification numbers assigned to businesses in the United States.

Although they are commonly used, in some cases interchangeably, a TIN and EIN are different.

What is a TIN number?

TIN is a general term used to refer to a taxpayer ID number.

The purpose of a tax ID number is to allow the U.S. tax authorities, the IRS, to administer the U.S. tax laws.

By generally referring to a tax identification number, a person may be referring to one or another tax ID number issued by the IRS or the Social Security Administration.

When do you need a TIN?

You need a tax identification number whenever you are filing taxes, corresponding with the tax authorities regarding your file or to provide documentation.

A TIN is any type of unique tax identification number allowing the IRS and tax authorities to associate the right file with the right person or entity.

What is an EIN number?

An Employer Identification Number or EIN is a number issued by the IRS who must file for taxes in the United States.

EIN is also referred to as Federal Employer Identification Number (FEIN) or Federal Tax Identification Number (FTIN).

EIN and TIN differences?

The main difference between EIN and TIN is with regard to the type of tax ID number you are referring to.

EIN is a specific type of tax ID number issued to businesses while TIN is a general term referring to many types of tax ID numbers.

For example, when you refer to an EIN number, you are specifically referring to a tax ID number assigned to a company.

When you refer to a TIN, you are generally referring to a tax identification number assigned to a taxpayer.

The tax ID number can be any tax ID number such as EIN, ATIN, PTIN or other.


EIN is a tax identification number issued to a business in the United States such as an S-Corp, C-Corp, LLC or partnership while an ITIN is a number assigned to an individual.

EIN stands for Employer Identification Number and ITIN stands for Individual Tax Identification Number.

ITIN numbers are issued to individuals who must report taxes to the IRS but who are not eligible to have a social security number (SSN).

ITNI and EIN serve the same purpose.

They both represent a unique ID number 


An EIN and FEIN are the exact same thing.

EIN stands for Employer Identification Number while FEIN stands for Federal Employer Identification Number.

They both refer to the same tax ID number.

You can refer to an EIN number in several ways: 

  1. EIN “Employer Identification Number”
  2. FEIN “Federal Employer Identification Number”
  3. FTIN “Federal Tax ID Number”


TIN vs FEIN is the same thing as TIN vs EIN.

Essentially, EIN and FEIN mean the same thing.

TIN refers to all types of tax identification numbers whereas FEIN refers specifically to the Federal Employer Identification Number.


EIN tax ID is issued to businesses as a unique identification number for tax purposes.

An individual, on the other hand, can use his or her SSN to file taxes and correspond with the tax authorities.

The taxpayer identification number for businesses is EIN and individuals SSN.

What about sole proprietors who are running a business under their own name?

Do they need an EIN or can they use their SSN?

Sole proprietors can use their SSN for tax purposes if they do not have any employees and do not need an EIN unless they incorporate their business or operate it as an LLC.

Taxpayer Identification Number FAQ’s

What is a tax ID number?

Many people ask what is my tax ID number?

A tax ID number is a unique number assigned to a person or entity for tax administration purposes.

Tax ID numbers (TIN) are generally assigned by the IRS and they can be referred to as:

  1. Federal Tax Identification Numbers
  2. FTIN
  3. Federal Employer Tax ID
  4. 95 Number
  5. 95-Number
  6. E.I.N. Number
  7. Tax I.D. Number
  8. Tax-ID Number

These terms refer to the nine-digit number or taxpayer-identification number assigned to a taxpayer for tax purposes. 

What is the SSN meaning?

SSN means “Social Security Number”.

SSN is a widely used acronym to refer to a person’s national identification number in the United States.

Is my Tax ID my SSN?

For individuals filing their taxes, your Tax ID or TIN is in fact your social security number.

The IRS administers the taxes for individuals through their unique SSN numbers.

American citizens, permanent residents and temporary nonimmigrant workers are assigned a social security number as their TIN.

Otherwise, if an individual must file taxes in the United States and is not eligible to get an SSN, they will be issued an ITIN or an Individual Taxpayer Identification Number.

How long does it take to get an EIN?

By applying online, you can get your EIN number very quickly.

According to the IRS, “you can get an EIN immediately by applying online”.

By faxing a request, the IRS will respond within a week or two.

By applying for an EIN by mail, it may take four to five weeks for the application to be processed.

Who is eligible for a social security number?

There are three categories of US individuals who are eligible to get an SSN:

  1. US citizens
  2. Permanent residents
  3. Temporary workers

A US citizen is a person who is granted citizenship of the United States and has the right to permanently live in the country, vote, get a US passport and work in the United States.

A permanent resident is a person who is given the right to live and work in the United States under the US immigration laws and cannot carry a US passport, vote or exercise the same rights as a US citizen.

A temporary nonimmigrant worker is a person who is not a resident of the United States but is given authorization to temporarily study or work in the United States.

How do I apply for an SSN if I’m an immigrant?

If you are an immigrant, you can apply for an SSN in your home country through the Social Security Field Office.

Generally, you can apply for an SSN at the same time as you file for your visa.

You can consult the Social Security Administration’s website for more information on Social Security Numbers and Immigrant Visas.

You can also consult the Foreign Workers and Social Security Numbers guide published on the SSA’s website.

How do I apply for a SSN if I’m not an immigrant?

If you are a non-immigrant, you should visit the Social Security Office in the United States to apply for an SSN.

To find the Social Security Office near you, you can use the Social Security Office Locator offered on the SSA’s website and enter your zip code.

What do the first 3 digits of your social security mean?

Historically, the first 3 digits of the social security number represented the geographical area of where the person was born.

However, since June 25, 2011, the IRS has stopped assigning social security numbers on this basis.

Today, the IRS issues SSN numbers randomly and the number no longer has any association or connection with where a person was born.

Is national ID the same as Social Security Number?


Historically, SSN was used to keep track of the earnings of those who worked in an employment covered by the social security program.

As of 1943, following the Executive Order 9397, the US authorities used social security numbers to keep track of all individuals instead.

Eventually, SSN became an American’s National ID number.

What are the tax ID number formats?

The IRS and the SSA issue TIN numbers to identify individuals or businesses for tax purposes.

Here is how the TIN numbers are formatted:

  1. Social Security Number (SSN Format): XXX-XX-XXXX
  2. Employer Identification Number (EIN Format): XX-XXXXXXX
  3. Individual Taxpayer Identification Number (ITIN Format): 9XX-XX-XXXX

We do not have a TIN format to show as TIN does not refer to a specific tax number but rather refers to a group of numbers.

What is a tax ID number example?

Tax ID numbers are considered confidential information.

Individuals must make sure they take all the necessary precautions to protect their SSN to avoid identity theft and other unauthorized activities.

The examples of Tax ID numbers we’ll give here are evidently fictitious:

  1. Example of SSN number: 123-45-6789
  2. Example of EIN number: 12-3456789
  3. Example of ITIN number: 912-34-5678

What is the difference between EIN and ATIN?

As opposed to the other taxpayer-identification numbers like an SSN, ITIN or EIN, ATIN is issued on a temporary basis.

The purpose is to issue a temporary tax identification number to a person who is adopting a US child but cannot get a social security number for that child.

ATIN is only issued in very specific circumstances such as when a person is adopting a US child.

On the other hand, an EIN number is a permanent number assigned to a business for tax purposes.

For so long as that business exists, the IRS will recognize that business with its EIN number.

What is the difference between EIN and PTIN?

The EIN number and PTIN number have very different purposes.

Whereas an EIN number is assigned to a business so they can pay taxes and get tax credits, a PTIN number is issued to a person who prepares taxes for another person or business for a fee.

A person who prepares taxes for others must mandatorily use his or her PTIN number on your tax when filing them with the IRS.

What is a foreign tax identifying number?

A foreign tax identifying number or Foreign TIN is issued by a foreign country to a non-U.S. taxpayer paying taxes in that country.

For example, a Canadian will have a Social Insurance Number (SIN) which is the equivalent of the SSN in the United States.

In the United States, the person’s SIN will be considered as a foreign tax identifying number.

What is a FEIN number?

FEIN is the abbreviation for Federal Employer Identification Number.

To understand what FEIN means, you must know what EIN means as they are both the exact same thing. 

EIN is a unique IRS tax ID issued to a business that must report its taxes to the US tax authorities or claim refunds.

FEIN number can also be referred to as Federal Tax ID Number, Federal EIN Number, FTIN, Federal TIN, EIN, Federal EIN or any other variations.

Where to find my TIN?

The U.S. Taxpayer Identification Number can be found in several documents such as:

  1. Tax returns
  2. Social security card 
  3. Correspondence with IRS
  4. Tax ID issuance certificates 

What forms do I need to apply for a TIN?

Depending on the type of tax ID number you need, there may be different forms you need to complete.

To help you out, we outline some of the most common forms used to get a TIN number:


Employment Identification Number

Form SS-4

EIN Application for Puerto Rico employers

Form SS-4PR

Social Security Card

Form SS-5

Individual Taxpayer Identification Number

Form W-7

ITIN application in Spanish

Form W-7(SP)

Application for Taxpayer Identification Number for Pending U.S. Adoptions

Form W-7A

Preparer Tax Identification Number

Form W-12