# Illinois — State mini-WARN act thresholds: layoff notice requirements beyond federal WARN

For Illinois, employer covered when is "Employer" means any business enterprise that employs: (1) 75 or more employees, excluding part-time employees; or (2) 75 or more employees who in the aggregate work at least 4,000 hours per week (exclusive of hours of overtime); notice triggered by is a plant closing — a shutdown resulting in an employment loss at the single site of employment during any 30-day period for 50 or more employees excluding any part-time employees — or a mass layoff resulting in an employment loss during any 30-day period for at least 33% of the employees and at least 25 employees (excluding part-time), or at least 250 employees; statute is 820 ILCS 65/5, verified against its source on 2026-08-18.

- **State:** Illinois _(our reading, not quoted from the source)_
- **Employer covered when:** "Employer" means any business enterprise that employs: (1) 75 or more employees, excluding part-time employees; or (2) 75 or more employees who in the aggregate work at least 4,000 hours per week (exclusive of hours of overtime) _(verified: appears in the quote below)_
- **Notice triggered by:** a plant closing — a shutdown resulting in an employment loss at the single site of employment during any 30-day period for 50 or more employees excluding any part-time employees — or a mass layoff resulting in an employment loss during any 30-day period for at least 33% of the employees and at least 25 employees (excluding part-time), or at least 250 employees _(verified: appears in the quote below)_
- **Statute:** 820 ILCS 65/5 _(verified: appears in the quote below)_
- **Notice period:** An employer may not order a mass layoff, relocation, or employment loss unless, 60 days before the order takes effect, the employer gives written notice of the order _(per ilga.gov, not stated by the source above)_

## What the source says

> (c) "Employer" means any business enterprise that employs: (1) 75 or more employees, excluding part-time | | employees; or | | (2) 75 or more employees who in the aggregate work at | | least 4,000 hours per week (exclusive of hours of overtime). | | (d) "Mass layoff" means a reduction in force which: (1) is not the result of a plant closing; and (2) results in an employment loss at the single site | | of employment during any 30-day period for: | | (A) at least 33% of the employees (excluding any | | part-time employees) and at least 25 employees (excluding any part-time employees); or | | (B) at least 250 employees (excluding any | | part-time employees). | | (e) "Part-time employee" means an employee who is employed for an average of fewer than 20 hours per week or who has been employed for fewer than 6 of the 12 months preceding the date on which notice is required. (f) "Plant closing" means the permanent or temporary shutdown of a single site of employment, or one or more facilities or operating units within a single site of employment, if the shutdown results in an employment loss at the single site of employment during any 30-day period for 50 or more employees excluding any part-time employees.

## Sources disagree

More than one authority states this, and they do not state the same
thing. Both are reproduced with the source each came from.

### Statute

ilga.gov says statute is **820 ILCS 65/5**, as of 2026-08-18.

> (c) "Employer" means any business enterprise that employs: (1) 75 or more employees, excluding part-time | | employees; or | | (2) 75 or more employees who in the aggregate work at | | least 4,000 hours per week (exclusive of hours of overtime). | | (d) "Mass layoff" means a reduction in force which: (1) is not the result of a plant closing; and (2) results in an employment loss at the single site | | of employment during any 30-day period for: | | (A) at least 33% of the employees (excluding any | | part-time employees) and at least 25 employees (excluding any part-time employees); or | | (B) at least 250 employees (excluding any | | part-time employees). | | (e) "Part-time employee" means an employee who is employed for an average of fewer than 20 hours per week or who has been employed for fewer than 6 of the 12 months preceding the date on which notice is required. (f) "Plant closing" means the permanent or temporary shutdown of a single site of employment, or one or more facilities or operating units within a single site of employment, if the shutdown results in an employment loss at the single site of employment during any 30-day period for 50 or more employees excluding any part-time employees.

Source: https://www.ilga.gov/legislation/ilcs/documents/082000650K5.htm

ilga.gov says statute is **820 ILCS 65/10**, as of 2026-08-18.

> (a) An employer may not order a mass layoff, relocation, or employment loss unless, 60 days before the order takes effect, the employer gives written notice of the order

Source: https://www.ilga.gov/legislation/ilcs/documents/082000650K10.htm


## Source

- https://www.ilga.gov/legislation/ilcs/documents/082000650K5.htm
- https://www.ilga.gov/legislation/ilcs/documents/082000650K10.htm

Last verified: 2026-08-18. Review by: 2027-08-18.
Part of [State mini-WARN act thresholds: layoff notice requirements beyond federal WARN](https://referencesource.org/state-mini-warn-act-thresholds/).