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.
You will need the following to get your CSN:
- Your social security number.
- A copy of your original 2007 California tax return. (If you didn't file a 2007 California return, click here for information about getting your CSN.)
- The California Adjusted Gross Income (AGI) from your 2007 tax return. (Use the chart below to find the line numbers.)
Form Number Line Numbers Form 540 2EZ Line 16 Form 540A Line 17 Form 540 Line 17 Form 540NR (Long) Line 21 Form 540NR (Short) Line 21