withholding Local taxes

I am in Illinois and I have an employee that lives in Indiana, but works for us in Illinois most of the time, so he is set up in our Payroll that his wages get applied to IL but when is is not coded to the Indiana job we have his set up is still taking out the Local Tax only??  is this correct?  since we cannot predict if he will be working at our Indiana job over 30 hours this year (job almost complete)  and at the end of year for 2024 the employee can file for a refund for these taxes?