Foreign income earned while a resident in IL

[samchase101]

I have a client that is married and his family lives in IL.  He owns a home there and his daughter is finishing high school in 2020.  From January to Sept he is a doctor and made W2 income.

He is has taken a job in China in Sept. of 2019 and has made around $100,000 for the end of 2019.  He claims he and his family will follow him to China when his daughter finishes high school in 2020.

I know he is obligated to pay federal taxes, but does he owes IL taxes on the $100k?

[Anonymous]

do you prepare the return for compensation? 

[samchase101]

I reported the 100k as income on the 1040 and I took a foreign tax credit for the taxes he paid to China, but does he need to include this income in IL and pay taxes in IL?