An Employer Identification Number , abbreviated to EIN, is a tax identification number issued by the Internal Revenue Service. California registered business entities must get an EIN before getting a State Employer Identification Number issued by the Employment Development Department. For business owners that have misplaced either of these numbers, find them through business records or directly at the issuing entity.

Check Existing Records

When the IRS issues an EIN, it sends a confirmation letter known as Form CP-575. This is the official confirmation used by financial institutions to confirm tax information when opening business checking accounts, credit cards or small business loans. The bank may have kept a copy of the form, but at the very least, the bank will have the EIN information on file as part of the account information. Go to the bank with a photo ID and ask a representative for account information verification and a copy of any documents on file.

Previous years' tax returns and payroll information also have this information. Go through old forms and documents. Do keep in mind that if you need to open a new financial account, you might need the CP-575 to confirm the number, rather than just have the number on hand.

Contact the IRS

Call the IRS Business and Specialty Tax Line between the business hours of 7:00 a.m. to 7:00 p.m., Mondays through Fridays. The direct department line is 800-829-4933. Provide the representative with the requested information; only authorized representatives can confirm an EIN, so the representative will ask to confirm identifying information. Authorized representatives include sole proprietors, named corporate officers, trustees or named partners.

The IRS will give you the EIN over the phone. If you need to replace the confirmation letter, Form CP-575, the representative will process the request to have that sent. It does take up to two weeks to receive the confirmation letter.

Contact the Employment Development Department

California requires the State Employer Identification Number or SEIN for state business tax returns, payroll and unemployment processing. If you specifically need the SEIN, contact the state Employment Development Department. Call during business hours from 8:00 a.m. to 5:00 p.m., Mondays through Fridays to reach a representative. The process will be similar to calling the IRS, requiring an authorized agent to confirm identifying information such as legal name and date of birth. The EDD provides SEIN confirmation over the phone. If you need written confirmation of the SEIN, this may take two to three weeks to generate. For faster service, visit a local EDD tax office. The EDD website has an office locator.