Four business days: the 8-K rule that is longer than it looks, and shorter

Everyone in a reporting company can recite the 8-K rule: four business days. The exact words from Form 8-K's General Instruction B.1 are "Unless otherwise specified, a report is to be filed or furnished within four business days after occurrence of the event." What trips people is the sentence immediately after it, and the handful of items where the clock does not start at the event at all.

The weekend sentence

Here is the part most summaries drop:

If the event occurs on a Saturday, Sunday, or a holiday on which the Commission is not open for business, the four-business-day period "shall begin to run on, and include, the first business day thereafter."

Read that word include carefully, because it does something unintuitive. An event on Friday gives you the next four business days — Monday, Tuesday, Wednesday, Thursday. An event on the Saturday immediately after gives you Monday as day one, so you land on Thursday as well. The Saturday event does not buy you an extra day. A Friday close and a Saturday close have the same deadline.

The same logic applies to holidays. An event on Monday, January 19, 2026 — the observed Birthday of Martin Luther King, Jr. — starts its clock on Tuesday the 20th, counting Tuesday as day one, and lands on Friday the 23rd.

The items whose clock starts somewhere else

Three cases are worth memorizing because getting them wrong shifts the date by days, not hours.

Item 1.05, material cybersecurity incidents. The four business days run from the point at which you determine the incident is material — not from discovery. That is not a loophole: the determination itself must be made without unreasonable delay after discovery. Practically, this means the compliance question is "when did we decide, and can we show that we decided promptly," not "when did the SOC ticket open."

Item 5.07, submission of matters to a vote. The period "shall begin to run on the day on which the meeting ended." For a single-day annual meeting the difference is small; for an adjourned meeting it is not. Item 5.07(d) is carved out of that rule and travels on its own schedule.

Items 2.02 and 7.01. These are *furnished*, not filed — information furnished under them is not deemed "filed" for Section 18 purposes. The four-business-day timing still applies; the liability posture is what differs. Companies routinely furnish an earnings release under 2.02 while filing something else in the same report, and the cover page has to reflect that correctly.

There is no NT 8-K

This is the one that surprises people who spend most of their year in periodic reports. Rule 12b-25 — the notification of late filing that buys 15 extra calendar days on a 10-K and 5 on a 10-Q — applies to Forms 10-K, 20-F, 11-K, 10-Q, 10-D, N-CSR, and N-CEN. Form 8-K is not on that list. There is no NT 8-K, no automatic extension, and no cure period. Four business days is the entire runway, and a late 8-K is simply late.

That asymmetry is worth building your internal process around. A 10-K slipping by a week is a bad quarter; an 8-K slipping by a week is a disclosure failure with nothing to file behind it.

What a tool can and cannot decide for you

Timing is arithmetic and should be automated. Whether the event is reportable is not. No calculator can tell you whether an agreement is a "material definitive agreement," whether an impairment is material, or which item a messy fact pattern belongs under — those are judgments, and they belong to your securities counsel. What software should do is take the decision you have already made, apply B.1 literally including the weekend sentence and the item-specific clocks, and hand you a date you can defend.

We built exactly that, free, at [unfoldcfo.com/free/8-k-deadline](https://www.unfoldcfo.com/free/8-k-deadline) — pick the item, enter the trigger date, and see both the deadline and the reason the clock started where it did.

Sources. Form 8-K, General Instruction B.1 and Items 1.05, 2.02, 5.07 and 7.01 (sec.gov); 17 CFR 240.12b-25(a) (eCFR); observed federal holidays under 5 U.S.C. 6103. General information, not legal advice — the Commission's own closure calendar and your counsel govern.