How to Find a California Tax ID Number EIN

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An employer tax identification number, commonly called EIN, is the business equivalent of an individual's Social Security number. It is used on tax and other state and federal documents to identify a business. The EINs required for state tax purposes by the California Franchise Tax Board are those issued by the federal Internal Revenue Service. Like a Social Security number, an employer identification number is considered confidential by the business and only provided on a need-to-know basis.

Look for the employer tax identification number on any tax return filed by the company, if you work for the company or have access to the returns. Find a company's California employer account number on any California employment tax filing.

Read More: How to Search for Tax ID Numbers for Businesses

Contact the company directly to obtain its tax identification number if you do not work for the company but have a legitimate reason to obtain the number. Send a letter requesting completion of an IRS Form W-9, and enclose the form. The W-9 form provides the employer's name and tax identification number. You can obtain the form from the IRS or online legal services providers.

Locate a misplaced identification number by finding the official document on which the IRS issued the number. You can also contact any banks or agencies to whom the company provided the number as part of an account application. Alternatively, contact the Internal Revenue Service Business & Specialty Tax Line, (800) 829-4933, from 7:00 a.m. to 7:00 p.m. weekdays. Be sure you have information about the original filing in order to confirm your right to the number.


  • The nine-digit EIN must be distinguished from the SEIN, an eight-digit employer account number required for interactions with the California Employment Development Department.


  • Use an IRS form SS-4 to request a new federal EIN number. You can also call the IRS and request a new EIN over the telephone.