Live in Illinois, worked in California

[The Doctor]

My son works seasonally for the National Park Service. Last year he worked for the summer in California, and paid CA state tax. He is a full time resident in Illinois. The 2 years prior, he worked in Michigan which has a reciprocal agreement with Illinois, making filing a little easier.

I'm looking for the best way to handle this. Do I need to purchase the CA state software and file as a non resident?

TIA

[Mike9241]

he needs to file a non-resident CA return and a resident IL return. on iL he takes credit for the CA taxes. IL schedule CR

[DavidD66 · Accepted solution]

Yes, your son will have to file a California Non-Resident tax return, in addition to his Illinois state tax return.  As an Illinois resident, 100% of his income is taxable by Illinois.  However, they will give your son a credit for state tax paid to California.  The credit is not a dollar for dollar credit; rather, it is calculated as the amount of Illinois tax that would be paid on the California income.  It may not be as much as the California tax, but it won't be more.