What is the definition of a part-time resident for Indiana for tax purposes?

Our convoluted situation is the following: We lived aboard a boat in Indiana waters for 7 months, worked during this time in Illinois but maintained our resident status in Florida.

Are we required to file Indiana taxes?

Many thanks in advance for you help!

Indiana probably considers you to be a part-year resident, as their waters are considered to be part of Indiana.

However, check to see if there is a reciporcity agreement between Illinois and Indiana that allows you to file only ONE state return. A check of either state's tax website should yield an answer.

Otherwise, legally, you should file returns for BOTH Illinois and Indiana.