For most U.S. citizens and residents, your taxpayer identification number is your social security number. If you are an alien who is not eligible for a social security number, you may need to apply for an individual taxpayer identification number for income tax purposes. And if you start a business as a sole proprietorship, or form a partnership or corporation, you will need an employer identification number.
Social Security Number
If you have a social security number, and you have to file a U.S. individual income tax return, you must include your social security number on your return. If you file a paper return, remember to write in your social security number because in order to protect your privacy, it is not printed on the peel-off label with your name and address.
Married Taxpayers
If you are married, you must include both spouses’ social security numbers, whether you file jointly or separately. If you file jointly, report your social security numbers in the same order as the names are presented.
Changes
If you changed your name during the year because of marriage, divorce, or another reason, you should inform the Social Security Administration so that their records are consistent with IRS records.
Dependents
You will also need taxpayer identification numbers for each dependent you claim on your return. This is generally the person’s social security number.
If you, your child or other dependent does not have a social security number, you should go to your local Social Security Administration office and complete Form SS-5 – Application for a Social Security Card. You will need to show proof of:
Age (birth certificate)
Identity (passport, driver’s license)
Citizenship or
Legal alien status (Immigration & Naturalization Service documents)
Aliens
Aliens who have been lawfully admitted to the United States for permanent residence, or who have entered the country under another immigration category that authorizes them to work, can generally obtain a social security number. In requesting a social security number, aliens need to present Form SS-5 with proof of identity, age, immigration status, and authorization to work in the United States.
Foreign students in the United States under an F-1 or M-1 visa will need to show their Form I-20. Visitors with a J-1 visa will need to show their Form DS-2019.
Adoption Taxpayer Identification Number
If you have an adopted child living in your home, who you can claim as a dependent, but for whom you have not yet been able to get a social security number, you can request an Adoption Taxpayer Identification Number (ATIN) by filing Form W-7A with the IRS.