Business Laws Guide: Federal, Illinois and Cook County

A small business answers to three layers of law at once. Federal law applies across the country, although many federal rules start only above a certain size. Illinois law applies to work, sales and filings in the state. In Cook County, county ordinances sit on top of both. This section explains 36 of these laws in plain English, with figures and dates checked against official sources. It is general information from a CPA firm, not legal advice. Please read the disclaimer and terms of use first.

How the section is organised

• Federal laws: pay and hours, job discrimination, workplace safety, income and payroll tax, ownership and cash reporting, advertising and email, competition, the environment and privacy.
• Illinois laws: LLCs, corporations and partnerships, contracts and consumer protection, wages, human rights, safety, non-competes, privacy, and state income and sales tax.
• Cook County laws: paid leave, minimum wage, business licensing and human rights, all limited to Cook County.

How to read a law's three pages

Every law has three short pages. The overview says what the law is, who it covers and what the main number and deadline are. The rules-and-numbers page lists each requirement, dates every figure, and covers recent changes and penalties. The checklist page offers a named checklist, common mistakes, situations where an attorney is the right person to ask, and frequently asked questions.

Which level of law applies to what

The levels often stack. For the minimum wage, an employee covered by both gets the higher of the federal and state rate, which in 2026 means Illinois's $15.00 (for employers with four or more employees) rather than the federal $7.25.

Four tools pull the section together: which laws apply by employee count, Illinois entity types compared, who enforces what and the business law calendar. The payroll and tax side is covered in our payroll guides and on the Illinois state page.