Aggregate Every Layoff Inside 90 Days Before the WARN Act's Notice Rule Finds You

The Signal

The federal WARN Act trips at 50 employees at a single site, or a third of the workforce there, in a single event. A lot of operators stop reading right there and check whether this round of cuts clears that bar. The Act doesn't stop at a single event. If a company runs two or three smaller reductions at the same site inside a rolling 90-day window, the Department of Labor adds them together and tests the combined headcount against the same threshold — even if nobody planned it that way and even if each round looked small enough on its own to skip notice entirely.

Why this matters now

Reductions rarely happen as one clean announcement anymore. A company trims an underperforming team in month one, closes a product line in month two, and restructures a support function in month three — three separate decisions, three separate managers, no single person tracking that they land on the same site inside the same 90 days. Each round gets evaluated on its own against the 50-employee threshold and clears it. The aggregation rule doesn't care that the decisions were separate. It looks at the site and the calendar.

The mistake to avoid

The mistake is evaluating each layoff round in isolation instead of against a rolling 90-day site total. HR or legal checks "is this round, by itself, 50 people or a third of the site" and gets a clean no, so notice gets skipped. Then round two lands eight weeks later at the same facility, and the DOL's math isn't round-by-round — it's the sum of every employment loss at that site in the trailing 90 days. A company can sail through three individually-compliant rounds and still owe 60 days' notice retroactively on round two, because round one plus round two crossed the line nobody was tracking.

The 90-day lookback employers miss

The rule runs in both directions from any reduction date, not just forward. A round planned today has to be checked against everything that already happened at that site in the past 90 days, and the company has to flag that a future round inside the next 90 days could trigger retroactive liability on the current one. Most RIF planning treats each round as a fresh slate. The WARN aggregation clock doesn't reset between rounds — it's a continuously rolling 90-day window measured at the site level, and a site that's had any headcount reduction in the last three months needs that history pulled before anyone signs off on a new one.

What stays protected

None of this changes the business decision to reduce headcount, the timeline the company needs to move on, or the confidentiality around who's affected until the decision is final. The fix sits entirely in the compliance review step before a reduction is executed — pulling the site's reduction history and running the aggregated math — not in how the reduction itself gets planned, communicated, or carried out. The operating decision stays with the business leader who made it; the clock-check is a separate, narrow legal step layered on top.

The first move

Pull the headcount-loss history for every physical site for the trailing 90 days from today — every layoff, every facility closure, every reduction categorized as a "mass layoff" or "plant closing" under WARN's definitions, regardless of which business unit ordered it. For any site with more than one event in that window, add the employment losses together and check the combined total against the 50-employee / one-third-of-site threshold. Do this before the next reduction at any site that's had cuts in the last quarter, not after.

The move this week

Build a standing site-level reduction log that every business unit's HR or legal partner has to check before signing off on a layoff, plant closing, or relocation at that site — one row per event, with date, headcount affected, and a running 90-day total. Require that check as a gate in the approval process itself, not a courtesy email. If the running total at any site is within 15 employees of the WARN threshold, treat the next planned reduction at that site as notice-triggering until counsel confirms otherwise — the penalty for guessing wrong is back pay and benefits for each affected employee for every day notice was short, up to 60 days, plus civil penalties to the local government that didn't get its required notice either.