Referring to the Gregorian Calendar?

Today I glanced at this Littler newsletter, which discusses a case involving a dispute over forum selection. But what caught my eye wasn’t the dispute itself. It was the language at issue:

This Agreement is subject to the provisions of the Labor Law No. (58) for the year 1970 Gregorian and its amendments and the law on Social Solidarity No. (13) for the year 1980 Gregorian and its amendments and all other decision, decree or regulation which have not been specifically mentioned in this Agreement.

Perhaps I lead a sheltered life, but I don’t recall having seen in a contract a reference to the Gregorian calendar, which is the calendar system initially adopted in 1582 by Catholic countries in Europe and now used almost everywhere in the world for civil purposes.

So of course I went on EDGAR, where I found references to the Gregorian calendar in 22 documents filed in the past year.

The following example is from an asset purchase agreement between a Japanese buyer and sellers from Delaware and Switzerland:

Unless the context otherwise requires, references herein to … a month, quarter and year are references to a month, quarter and year of the Gregorian Calendar ….

The following is from a joint venture contract between parties from Japan and China:

The Company shall use Gregorian calendar for its financial year, which shall commence from 1st January and end on 31st December of each year.

And the following is from a Colombian oil-and-gas contract:

Year: It refers to the term of twelve (12) consecutive months according to the Gregorian Calendar, counted as of a specific date.

And the following is from an oil-and-gas operation agreement between a Delaware company and an English company:

Calendar Year means a period of twelve (12) months commencing with January 1 and ending on the following December 31 according to the Gregorian Calendar.

What other calendars are there besides the Gregorian calendar? Go here for a list on Wikipedia. But in my search of contracts filed in the past year on EDGAR, I found no references to any calendar system other than the Gregorian calendar.

So, readers: When, if at all, is it advisable to refer to the Gregorian calendar? Have you encountered references to any other kind of calendar?

About the author

Ken Adams is the leading authority on how to say clearly whatever you want to say in a contract. He’s author of A Manual of Style for Contract Drafting, and he offers online and in-person training around the world. He’s also chief content officer of LegalSifter, Inc., a company that combines artificial intelligence and expertise to assist with review of contracts.

20 thoughts on “Referring to the Gregorian Calendar?”

      • I don’t think so. A “month” (in English law) is (now) usually interpreted as running from a specific numbered day in one month to the same (or last – whichever is the lesser) of the next.

        • Agreed. Three months’ notice to terminate a contract, given today (15 November 2013) expires at midnight at the end of 15 February 2014.

          • So in England, “calendar month” means the same as “month,” which means a period running from whatever day one month to the same day the next month? That’s not what U.S. courts say “calendar month” means. All the more reason never to use the adjective “calendar” and to be specific as to what “month” means.

          • Interesting. I didn’t know that. Similar issue for “quarterly” where dates should be specified otherwise (old) English case law suggests would be interpreted as “usual quarter days” when agricultural rents were due, ie Lady Day, Midsummer, Michaelmas and Christmas Day.

          • Mind you, I haven’t looked at the U.S. caselaw on “calendar month.” I’m applying the logic of caselaw on “calendar year,” which a large majority of courts have said means the twelve months beginning January 1.

          • Then perhaps I should shut my pie hole until I look further at U.S. caselaw. But this reminds me of the disaster that is “biannual” and “biennial.” Using the adjective “calendar” to mean one thing with “month” and something else with “year” is bizarre.

  1. The case discussed in the Littler note apparently involves Libyan law and Libyan courts. My hunch is that the employment agreement at issue in the case mentions the Gregorian calendar to avoid confusion with the Islamic calendar (or the particular calendar used in Libya – here is info on the Islamic calendar in general: ; and the Libyan calendar in particular: – this is just what I could gather from a Google search, I’m not an expert on this).

    I’ve seen one other example of explicitly choosing the Gregorian calendar, an operating agreement for an Israeli business entity. My hunch is that this is essentially the same idea: clarify that the operating agreement goes by the Gregorian calendar, not the Hebrew calendar (

    I guess that if you’re doing a cross-border deal that involves a jurisdiction that might not use the Gregorian calendar, it’s probably not a bad idea to say which calendar you’re using, if only to make sure everyone’s on the same page.

  2. With reference to the earlier discussion of lunar months, since that discussion I have drafted an agreement relating to internet gaming, where I was instructed to include a four-week accounting period in the agreement. I was tempted to define it as Lunar Month, but in the end decided to call it Accounting Month.

    • Thanks. For my part, I asked about this during my Abu Dhabi seminar, and I was told that it’s standard to refer to the Muslim calendar in contracts between local companies. I’ll inquire further at tomorrow’s in-house seminar.

    • A lunar month is very close to being 29 and a half days long, so just a bit longer than 4 weeks I’m afraid (it’s why lunar calendars had alternating 29 and 30 day months with an occasional fix).

      I have clients who can’t understand why *anyone* would want to use months at all. They tend to be tech. people who are irritated by the fact that “month” refers to different lengths of time.depending on the exact date. They like to be able to do exact calculations and having things done on weeks or groups of weeks just seems more rational.


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