The TurboTax software is asking you to make a manual calculation here, in order to determine "how much" of your student loan interest you can include on the state (not federal) column / portion of your California nonresident tax return.
In order to do this correctly, you will want download and have access to the Student Loan Interest Deduction Worksheet for California nonresidents, which is found on Page 46 of the following California Franchise Tax Board publication:
https://www.ftb.ca.gov/forms/2016/16_540nrbk.pdf
You will want to fill out that worksheet, and use the amount you get from Line 10 of that worksheet (or alternatively from Line 11, if you determine through the worksheet calculations that you have any number there other than $0).
But in order to complete that California worksheet, you will first need access to certain information (such as your federal student loan interest deduction amount) from your Form 1040 (or 1040A) federal income tax return. In TurboTax desktop you can view your forms directly. In TurboTax online, since you cannot view your forms directly, you would have to "
Preview Your 1040" by using the steps explained at the following link:
https://ttlc.intuit.com/questions/1901539-how-do-i-preview-my-turbotax-online-return-before-filingThus, in order to get your accurate student loan interest amount for a California nonresident return, here is what we recommend.
First, go to the top link above, and print the relevant table from Page 46 of the (2016) California nonresident instructions booklet.
Second, look at your federal tax return using the preview steps above. Locate your federal student loan interest amount, and any other numbers you need, and use them to fill out your California worksheet.
Third, return to the TurboTax California program and input the amount from Line 10 (or Line 11, if any) into the question field asking for your California student loan interest amount.
Fourth, finish the remainder of your tax return(s) normally.
Hopefully this will provide you with the tools and information you need to resolve this issue; and thank you for asking this important question.
