The 5 business day rule that decides whether FMLA is FMLA

Under 29 CFR 825.300(d)(4), the employer must provide the designation notice within 5 business days of having enough information to designate the leave as FMLA-qualifying.

This one sentence is the most expensive line in the entire regulation, because most employers anchor the 5-day clock to the wrong date.

The clock starts when you know, not when you're sure

"Having enough information to designate" means the moment the HR manager could reasonably conclude the leave qualifies under 29 CFR 825.113. It does NOT mean the moment you are absolutely certain.

If you wait to be certain, you will miss the window.

What happens if you miss the 5-day deadline

Two things:

The leave remains protected. You cannot retroactively undo the employee's FMLA rights because of your paperwork error.

You cannot count the leave against the 12-week entitlement for the period between when you should have designated and when you actually did. The employee keeps the 12 weeks AND the additional period of protected leave that ran during your paperwork gap.

This is per 29 CFR 825.301(e): "Failure to follow the notice requirements set forth in § 825.300 may constitute an interference with, restraint, or denial of the exercise of an employee's FMLA rights."

What Sentinel does with this rule

Every FMLA case in Sentinel opens with a prominent "Employer Response Window" card showing exactly how many business days you have left to get the designation notice out. The card is red when you're within 1 day of the deadline, orange when you're within 3, and neutral otherwise. Miss the deadline and the case shifts into an overdue state with the exact number of days you missed by.

You do not need to remember the rule. Sentinel remembers it for you.