Customer Service Number (CSN)

Your Customer Service Number (CSN) is your key to accessing your personal tax information online. 

Need more information? Check out our Frequently Asked Questions.

We issue a new CSN to every taxpayer each calendar year. The number is only valid during the year for which it is issued.

Step 1 - Make sure you have:

• Your Social Security Number.
• A copy of your original 2006 California tax return. (If you didn't file a 2006 California return, click here for information about getting your CSN.)
• The California Adjusted Gross Income (AGI) from your 2006 tax return. (Use the chart below to find the line numbers.)

Form Number	Line Numbers
Form 540 2EZ	Line 16
Form 540A	Line 14
Form 540	Line 17
Form 540NR (Long)	Line 21
Form 540NR (Short)	Line 21

Step 2 - Check your browser:

Before you begin, make sure you are using a And, we recommend that you log out and close your browser when you are done to ensure the highest level of security.

Step 3 - Select "Get CSN"