Can I (my son) File only State (IL) return to get tax refund

Not a product specific or e-file question... but, my son worked in summer and got W-2 (show zero tax paid to fed), which is much less than $14600, so he not need to file federal return. The W-2 also show tax were paid to IL. As the income is less than IL min income for return, he may entitled to get the IL tax paid from pay. So my question is, without using TT, can i just file IL tax return on IL Revenue website or may I just do this with paper copy and mail?

Thanks