2025.12.20 – A Two-Week Year-End Shutdown That Stays Clear in Every Calendar

Key Takeaways

The dates

A non-working period is set for December twenty-second, two thousand twenty-five through January fourth, two thousand twenty-six, both days included.

The count

The full break covers fourteen days.

The week numbers

The affected ISO weeks are week fifty-two of two thousand twenty-five and week one of two thousand twenty-six.

Story & Details

What this article is about

A year-end shutdown can sound simple, yet it often turns messy when it crosses from late December into early January. This piece is about one clear solution: name the shutdown dates, confirm the ISO week numbers, and place a matching all-day event into a shared calendar file.

The shutdown window

As of December twentieth, two thousand twenty-five, the shutdown is still ahead. It starts on Monday, December twenty-second, two thousand twenty-five, and ends on Sunday, January fourth, two thousand twenty-six. Both ends count. That makes fourteen days in total.

Why ISO week numbers matter

Many teams plan by ISO week. In this case, the break lines up neatly with two ISO weeks. ISO week fifty-two of two thousand twenty-five runs from Monday, December twenty-second through Sunday, December twenty-eighth. ISO week one of two thousand twenty-six runs from Monday, December twenty-ninth, two thousand twenty-five through Sunday, January fourth, two thousand twenty-six. The key detail is that ISO week one begins on a Monday, even when that Monday still sits in December.

The calendar file detail that prevents off-by-one mistakes

A simple iCalendar file, often saved with the .ics extension, can carry the shutdown as one all-day event. For all-day events, many calendar tools treat the end date as the first day that is not part of the event. That is why a shutdown that ends on January fourth is commonly stored with an end date of January fifth in the file, while still showing January fourth as the last day in the calendar app.

A short Dutch mini-lesson for real-world notices

In the Netherlands (Europe), short notices often aim for calm and direct language. These examples are practical and easy to reuse.

“Wij zijn gesloten van maandag tweeëntwintig december tweeduizend vijfentwintig tot en met zondag vier januari tweeduizend zesentwintig.”
Word-by-word guide: Wij = we; zijn = are; gesloten = closed; van = from; maandag = Monday; tweeëntwintig = twenty-two; december = December; tweeduizend vijfentwintig = two thousand twenty-five; tot = until; en met = and with; zondag = Sunday; vier = four; januari = January; tweeduizend zesentwintig = two thousand twenty-six. Tone: neutral and office-safe.

“Tot en met” is the small power tool in that sentence. It signals that the final day is included, not excluded. It is common in schedules, leave notes, and opening hours.

“Niet beschikbaar.”
Word-by-word guide: Niet = not; beschikbaar = available. Tone: short, firm, and normal in calendars. A softer option is “Even niet beschikbaar,” where Even adds a light “for a bit” feel.

Conclusions

A shutdown becomes easy to trust when it is said the same way in every place: in plain dates, in ISO week numbers, and in a calendar event that matches what people will see on their phones and laptops. With the period set from December twenty-second, two thousand twenty-five through January fourth, two thousand twenty-six, the year change stops being a source of confusion and becomes just a clean line in the plan.

Selected References

[1] https://www.iso.org/iso-8601-date-and-time-format.html
[2] https://www.rfc-editor.org/rfc/rfc5545.html
[3] https://datatracker.ietf.org/doc/html/rfc5545
[4] https://www.youtube.com/watch?v=wKJ0P0xKfCE

Appendix

All-day event

An event that covers a full date without a specific start hour, often shown as a banner across the day in a calendar.

Inclusive dates

A date range where the first day and the last day both count as part of the period.

ISO week

A week-number system where weeks start on Monday and are labeled so that planning stays consistent across years.

iCalendar

A standard format for exchanging calendar data, used by many tools to share events and schedules.

ICS file

A text file, usually ending in .ics, that holds iCalendar data so it can be imported into calendar apps.

Week boundary

The point where one labeled week ends and the next begins, which can matter when a plan crosses from one year into the next.