How do I calculate the California portion of my student loan interest deduction?

[danielaw]

I lived in California until mid-September 2016, then moved out of state. My 1098-E states (box 1) that I payed a total of $884.94 in student loan interest in 2016. Turbo tax determined that my federal adjusted student loan interest deduction is $885. Now it says "enter the California portion of your student loan interest deduction. If none, enter zero." How do I figure out what the California portion is?

[Phillip1 · Accepted solution]

The interest expense needs to be annualized. The first step is to divide the student loan interest by 12 months for the interest paid monthly, then the monthly amount needs to be multiplied by the number of months in CA (9.5).

1. 885/12 months = 73.75 per month.
2. 73.75 monthly interest X 9.5 months in CA = 700.63 CA Student Loan Interest.