The WARN Act, the Worker Adjustment and Retraining Notification Act, requires most US employers with 100 or more employees to give at least 60 calendar days' written notice before a plant closing or mass layoff. Notice goes to affected employees or their representatives, the state dislocated worker unit and the chief elected official of the local government.
Most small businesses will never trigger WARN. But growing companies cross the 100-employee line faster than they expect, and the rules count people and days in ways that aren't obvious. Here's how the federal rules work, from the Department of Labor and the regulations at 20 CFR Part 639.
Who the WARN Act covers
An employer is covered if it has either of these:
- 100 or more employees, not counting part-time employees
- 100 or more employees, including part-time employees, who together work at least 4,000 hours a week, not counting overtime
A part-time employee, for WARN, is someone who works an average of fewer than 20 hours a week, or who has been employed for fewer than 6 of the 12 months before notice is due. That second part catches people out: a full-time hire who joined four months ago counts as part-time for these tests. Workers on temporary layoff or leave who reasonably expect to be recalled still count as employees.
What triggers notice
| Event | What the regulations say |
|---|---|
| Plant closing | A permanent or temporary shutdown of a single site, or a facility or operating unit within it, that causes an employment loss for 50 or more employees, not counting part-time employees, in any 30-day period |
| Mass layoff | A reduction in force, not caused by a plant closing, that causes an employment loss at one site in any 30-day period for at least 33% of active full-time employees and at least 50 employees |
| Large mass layoff | Where 500 or more full-time employees are affected, the 33% test doesn't apply |
What counts as an employment loss
The regulations define an employment loss as one of three things: a termination, other than a discharge for cause, a voluntary departure or retirement; a layoff exceeding 6 months; or a reduction in hours of more than 50% in each month of any 6-month period. So deep, long hours cuts can count even if nobody is fired.
The aggregation rule that catches growing companies
This is the insight most managers don't know. You can't avoid WARN by splitting a layoff into smaller rounds. The regulations tell employers to look 30 days ahead and 30 days behind to see whether job losses, taken and planned together, reach the thresholds in any 30-day period. They also tell you to look 90 days ahead and 90 days behind: separate rounds that are each too small can add up across a 90-day period and still trigger notice. When employees leave on different dates, the first termination in that window starts the 60-day clock.
Who gets notice
- Each affected employee, or their representative if they're represented, such as by a union.
- The state dislocated worker unit, so help for workers can start quickly.
- The chief elected official of the local government where the closing or layoff will happen.
Managers and supervisors count as affected employees, alongside hourly and salaried staff. It's the employer's job to decide who in the business prepares and delivers the notices.
Exceptions and shorter notice
- Temporary facilities and projects: no notice is needed if the closing is of a temporary facility, or the layoff is the end of a particular project, and staff were hired knowing their work would last only that long.
- Faltering company: an exception that can reduce notice in limited cases where the business was actively seeking capital to stay open.
- Unforeseeable business circumstances: a sudden, unexpected event outside the employer's control can shorten the notice period.
- Natural disasters: the Department of Labor publishes a separate fact sheet on dislocations caused by natural disasters.
- Transfers: offering a transfer to a site within reasonable commuting distance, with no more than a 6-month break in employment, can mean there's no employment loss.
The exceptions reduce the notice period; they don't make the paperwork disappear, and the regulations expect an explanation of why notice is short.
If you're selling the business
In a sale, the seller is responsible for notice of any closing or layoff up to and including the effective date of the sale, and the buyer is responsible afterwards. The regulations suggest both sides work out the impact on staff before completion and agree who gives notice.
Enforcement and state laws
The Department of Labor's Employment and Training Administration administers WARN but has no role in seeking damages for workers. The law is enforced through private legal action in federal court, and the DOL won't issue advisory opinions on specific cases. Some states also have their own plant closing laws with different thresholds, so the DOL suggests contacting your State Dislocated Worker Unit. Its Rapid Response teams can also support your staff before a layoff with job search help and information on benefits.
Want AI doing the heavy lifting in your marketing?
I build the systems that handle the boring 80 percent, so you get your week back. Done properly, with the human kept in.
If you're planning headcount changes, HR software for small businesses makes it easier to track service dates and hours, and payroll software gives you the records you'll need.
My verdict
WARN is a big-company law that growing businesses meet without warning. The two traps are counting: who's part-time for WARN, and adding up layoffs over 30 and 90 days. If you're near 100 employees and planning cuts, map every role and date first, give the full 60 days whenever you can, and check your state's rules too.
Frequently asked questions
What is the WARN Act?
The Worker Adjustment and Retraining Notification Act, a US federal law requiring covered employers to give 60 calendar days' written notice of plant closings and mass layoffs.
Which employers does the WARN Act apply to?
Generally employers with 100 or more employees excluding part-timers, or 100 or more employees who together work at least 4,000 hours a week excluding overtime.
How many layoffs trigger WARN?
A plant closing affecting 50 or more full-time employees at a site, or a mass layoff of at least 50 employees and 33% of the site's full-time staff, or 500 or more employees regardless of percentage.
Can you avoid WARN by laying people off in stages?
No. The regulations add up job losses over 30-day and 90-day periods, so smaller rounds can still trigger notice together.
Who must receive WARN notice?
Affected employees or their representatives, the state dislocated worker unit and the chief elected official of the local government.
Who enforces the WARN Act?
It's enforced through private legal action in federal court. The Department of Labor administers it but doesn't seek damages for workers.
