Illinois and the ZIP-code proxy rule

Most AI hiring rules regulate what a tool produces. Illinois also regulates something it is fed: HB 3773 prohibits using ZIP code as a proxy for a protected characteristic. It is an unusually specific provision, and it catches something an outcome test would miss.

The provision

Why a postcode field is in an AI statute

A model does not need to be told someone's race, national origin or disability status to sort candidates along those lines. It needs a field that travels with them. In the United States, residential geography is one of the strongest such fields, for reasons that have nothing to do with hiring and everything to do with history.

So a tool that has never seen a protected characteristic can still reproduce one, and an employer running that tool can say — accurately — that no protected characteristic was ever supplied. The proxy rule closes that gap by naming the substitute directly.

What this reaches that an outcome test would not

The rest of HB 3773 is about outcomes: an employer may not use AI that discriminates on a protected characteristic. That is enforceable but retrospective — it needs a disparity to have occurred and been detected.

The proxy provision reaches the configuration instead. It applies to how the tool is set up, before any candidate is affected, which makes it a question for whoever selects and configures a hiring tool rather than for whoever reviews its results a year later.

Where the line actually falls

Knowing where a candidate lives is still allowed. Staffing runs on location: shift coverage, commute distance, site assignment and jurisdiction matching all depend on it. What the provision reaches is using the field as a stand-in for a protected characteristic in an employment decision, which is a different thing from holding an address.

Where the line falls in a specific configuration is a legal question. It is worth asking it of a vendor before a tool is adopted, because the answer is much cheaper to obtain then than after a charge is filed with the Illinois Department of Human Rights.

Where this sits relative to notice

It does not overlap with the notice duty at all. Notice is a workflow and records obligation, owned by recruiting operations. The proxy rule is a tool-configuration obligation, owned by whoever chooses and configures the tool. Meeting one says nothing about the other, and a records system, this one included, only helps with the notice.

Common questions

This page is general information about published government requirements, last reviewed August 26, 2026. Requirements change; confirm the current text with the agency and your own counsel before relying on it.