The WARN Act explained, with state rules

The federal WARN Act requires employers with 100 or more full-time employees to give 60 days’ written notice before a plant closing or mass layoff. A plant closing is a shutdown of a site that affects 50 or more employees in a 30-day period. A mass layoff is 500 or more employees at a site, or 50 to 499 if they are at least a third of the site’s full-time workforce. Several states have stricter laws: California applies from 75 employees, and New York from 50 full-time employees with 90 days’ notice.

Federal WARN at a glance

Question	Federal rule
Who is covered	Employers with 100 or more full-time employees (counting those with 6+ months in the last 12)
Notice period	60 calendar days before the closing or layoff
Plant closing	Shutdown of a single site affecting 50+ employees in a 30-day period
Mass layoff	50–499 full-time employees who are at least 33% of the site’s full-time workforce, or 500+ regardless of percentage, in a 30-day period
Who gets notice	Employees or their representative; the state dislocated worker unit; the chief elected local official
Legal basis	29 U.S.C. 2101 et seq.; 20 CFR Part 639

California and New York compared

	Federal	California	New York
Employer size	100+ full-time	75+ full- and part-time in the prior 12 months	50+ full-time in New York
Notice	60 days	60 days	90 days
Layoff trigger	50–499 at 33%+, or 500+	50+ in 30 days, regardless of percentage	25+ full-time at 33%+, or 250+
Closing trigger	50+ at a site	Any number at a covered establishment	25+ employees
Relocation	Not a separate trigger	Moves of 100+ miles are covered	See state rules

Other states, including New Jersey and Illinois, have their own WARN laws. Check the state labor department’s current page before you plan dates; we only list rules we have checked against an official source.

Planning steps

1. Count by site and by 30-day window. Layoffs spread across weeks can add up under the aggregation rules.
2. Decide dates with the notice period built in. If you cannot give full notice, ask counsel about the law’s limited exceptions and about pay in lieu of notice.
3. Write the notices to employees, the state dislocated worker unit and the local official, with the content the rules require.
4. Plan final pay and benefits under your state’s timing rules.
5. Keep the records of who was affected, why, and when notice was given.

Before access is switched off

People who leave take their knowledge with them, but their mailboxes, documents and tickets stay with the company. Transfer ownership of shared files, keep departing staff’s accounts in an archived state rather than deleting them, and follow your retention rules. That history matters for handovers, disputes and, for some companies, as a licensable asset.