Thank you for your question.
I'm sorry to hear of your trials and runarounds with local government minions.
Unfortunately, even official governmental websites are not always legally considered "controlling", to pluck a real legal term from one of Al Gore's most infamous statements. The state law concerning property taxes and exemptions is what truly controls at the first fundamental layer.
A person who is wrongfully denied protections of the law is wise to as fully document the denials of rights as possible. That usually means after a few unsuccessful face-to-face encounters, they start putting everything in writing. For over-the-counter transactions like what you describe, the document dance begins with:
A. Gather all of the so-called required and adequate documents into a nice package.
B. Add a cover letter that asks for whatever the governmental drone is supposed to do with the package.
C. Include a statement that [whatever source you got it from, like "your website" or "your brochure"] says that [list of documents] is required to obtain [whatever this request is].
D. Enclosed you will find [document list], which fully complies with your requirements.
E. Thank you for your assistance.
Then the intrepid quest-seeker makes a complete copy of the whole package for his or her own records.
A combative individual planning on civil rights litigation will then have a friend video record the next attempt to get satisfaction over the counter. Remaining polite and calm throughout the process is essential.
THEN when the "reasons" why the request is denied are given, the quest for the goal continues with "Could you please write down for me everything I'm missing so I can have it all the next time I come here?" The response or refusal is best recorded.
F.(a). IF there is a refusal to tell what more is needed, the whole package is then sent to the "top dog" in that office, with a second cover letter for the package describing what happened at the counter on such-and-such date and time, when the attached package was presented. Express befuddlement over being denied any additional help, and ask the top dog's assistance in getting the task done. At this point, it's a good idea to also cite the relevant state law and ask how what's in the package fails to satisfy the state law requirements. Again, keep a copy for yourself.
F.(b). IF there is some "help" that asks for all sorts of additional documentation that is NOT required by law, copy the helpful note and reference that in the type of top-dog letter described in F(a)., but expressing befuddlement over why all this extra stuff is required when the law mentions only what's in your enclosed package.
Then give them 7-10 calendar days to decide what to do with the troublemaker letter.
In the meantime, locate a person of different ethnic background who has successfully obtained the same thing, and get a checklist of everything THEY had to submit to get the job done. If it is notably less oppressive than what you have been *told* at that local county office, contact the local ACLU about a pro bono lawsuit for unlawful discrimination disguised as mere dereliction of duty.
The law you are trying to invoke is probably 35 ILCS 200/15-175. You can look up a good summary of the law, independent of your local county governmental drones' website, here: http://www.revenue.state.il.us/localgovernment/propertytax/taxrelief.htm
More information on one way governmental abuses can be addressed under one possible FEDERAL law is here (look for 18, U.S.C., Section 242): https://www.fbi.gov/about-us/investigate/civilrights/federal-statutes/#section242
Most of the time, official misconduct cases are pursued in civil lawsuits under 2 U.S.C. § 1983. They are often called "Section 1983" cases. That law allows a lawsuit against a “person who, under color of [state law], subjects, or causes to be subjected, any citizen of the United States . . . to the deprivation of any rights, privileges, or immunities secured by the Constitution and laws of the United States.”
Yes, often to correct local abuses, a person really does need to "make a federal case out of it".