Move a deadline or count an interval?
Choose the calendar rule before combining dates, weekly closures and holidays.
| Date | Weekly closure | Office closure | Counted |
|---|---|---|---|
| 2026-10-16 | No | No | Yes |
| 2026-10-17 | Yes | No | No |
| 2026-10-18 | Yes | No | No |
| 2026-10-19 | No | Yes | No |
| 2026-10-20 | No | No | Yes |
Start with the question
Moving one working day from Friday October 16, 2026 excludes that starting date. With Saturday and Sunday closed and Monday October 19 listed as an office closure, the next eligible date is Tuesday October 20. WORKDAY.INTL returns a date.
Counting the inclusive interval from that Friday through Tuesday gives two working dates: Friday and Tuesday. NETWORKDAYS.INTL returns a count. Subtracting the serial dates instead gives four calendar days and answers a different question.
Make the calendar explicit
A seven-character text mask starts with Monday: 0 means working and 1 means closed. A separate holiday list excludes specific dates. Repeated holiday rows and holidays already on a weekly closure do not remove extra dates. The dates in this example are invented office closures, not a country holiday calendar.
Use numeric dates or DATE expressions rather than ambiguous date text. Displaying a date as YYYY-MM-DD makes it readable while retaining its numeric value. The practice tasks explain their supported date ranges and leave unsupported inputs ungraded.
=NETWORKDAYS.INTL(DATE(2026,10,16),DATE(2026,10,20),"0000011",DATE(2026,10,19))Include a working month end
For the last working date on or before a month end, first find the calendar boundary with EOMONTH. Start one calendar day after that boundary, then move backward one workday. This includes the month end when it is already eligible; starting directly on it and moving back would skip it.
A zero workday offset leaves the start unchanged, including a closed date. A fully closed weekly mask produces zero when counting an interval, but cannot define an advancing deadline calendar.
=WORKDAY.INTL(EOMONTH(A2,B2)+1,-1,$G$2,$G$4:$G$7)Check the idea
Which date is one working day after Friday October 16 under this calendar?
Try the idea
References
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