If I look at a copyright notice, I see Copyright (c) <YEAR> <OWNER>. The part this question is about is the definition on <YEAR>.

The number represented in <YEAR> is based on the Gregorian calendar and shows the number of years passed since Anno Domini (or Common era). As there exist various different calendars around the world, I was wondering how this could affect the legal side, when using another calendar for copyright notice, or in contracts.


I came across the Holocene calendar which counts years since the Holocene epoch instead of Anno Domini (or Common era) as the Gregorian calendar does. As the Gregorian calendar date can be defined with <YEAR> AD or <YEAR> CE the Holocene calendar year can be defined with <YEAR> HE. So I was wondering if such a year definition format could be used in a contract and especially a copyright notice (for example Copyright (c) 12021 HE <OWNER>).

As there exist a variety of other calendars, I guess this question also regards those.

As a programmer I know that you should not touch a running system. So using another calendar in the current already well established system makes things more complicated and confusing. But sadly I have not found any resources defining a restriction on which calendar year to use.

  • 1
    Which jurisdiction? Because many jurisdictions don't prescribe copyright notices or their format in any way, whereas others like the US make very specific rules. Most likely, use of alternate calendars would make the notice invalid.
    – amon
    May 2 at 8:51
  • 2
    A copyright notice has often little to no bearing upon when the copyright expires.
    – Trish
    May 2 at 8:52
  • @amon As I live in Switzerland I would be interested in that. But as you mentioned, the US has very specific rules, it would also be interesting to know how such a case would be handled there.
    – TheEquah
    May 2 at 9:02
  • Use of a date in a different calendar in a contract is really a separqte3 issue governed by different laws, and should, I think, be a separate question. May 2 at 17:11


There seems no reason why a year in a copyright notice could not be specified with a calendar other than the Gregorian Calander, provided it is made clear what system of dates is being used.

US Law

In law the provision for a copyright notice is in 17 USC 401 which provides that:

(a) General Provisions.—Whenever a work protected under this title is published in the United States or elsewhere by authority of the copyright owner, a notice of copyright as provided by this section may be placed on publicly distributed copies from which the work can be visually perceived, either directly or with the aid of a machine or device.

(b) Form of Notice.—If a notice appears on the copies, it shall consist of the following three elements:

(1) the symbol © (the letter C in a circle), or the word “Copyright”, or the abbreviation “Copr.”; and

(2) the year of first publication of the work; in the case of compilations or derivative works incorporating previously published material, the year date of first publication of the compilation or derivative work is sufficient. ...; and

(3) the name of the owner of copyright in the work, or an abbreviation ...


(d) Evidentiary Weight of Notice.—If a notice of copyright in the form and position specified by this section appears on the published copy or copies to which a defendant in a copyright infringement suit had access, then no weight shall be given to such a defendant’s interposition of a defense based on innocent infringement in mitigation of actual or statutory damages, except as provided in the last sentence of section 504(2).

Note that subsection (a) says that the notice "may be placed" -- it is not required. Its only legal effect is that in subsection (d) where it defeats any claim of "innocent infringement".

Note also that while a year is part of the standard form of the notice, no calendar is specified by the law, and presumably any calendar could be used, provided that it was made clear which calendar was meant.

Berne Convention

Under the Berne Copyright Convention, to which almost all countries now adhere, no notice is required, and the term of copyright is not based on the date of publication except for anonymous works and works published under a pseudonym.

History, BA and UCC conventions

Under US law prior to the copyright act of 1976, a copyright notice was mandatory -- omitting the notice on a published work would cause loss of all copyright protection. Under that law the period of copyright was always computed from the date of publication, so the year of publication was essential to determine if a work was currently protected or not, and an incorrect year could also cause loss of protection.

Under the Buenos Aires Convention, and the Universal Copyright Convention countreis were permitted to require a copyright notice, and many did, who were not then adherent to the Berne Convention.

Article III paragraphs 1 of the UCC provided that:

Any Contracting State which, under its domestic law, requires as a condition of copyright, compliance with formalities such as deposit, registration, notice, notarial certificates, payment of fees or manufacture or publication in that Contracting State, shall regard these requirements as satisfied with respect to all works protected in accordance with this Convention and first published outside its territory and the author of which is not one of its nationals, if from the time of the first publication all the copies of the work published with the authority of the author or other copyright proprietor bear the symbol © acompanied by the name of the copyright proprietor and the year of first publication placed in such manner and location as to give reasonable notice of claim of copyright.

Notice that a year is required as part of the notice under the UCC, but as in US law, no particular calendar is specified, and presumably alternate calendars could be sued if this is made clear.


In some parts of Europe, the copyright notice has no bearing on the existence of copyright. At best, it removes the excuses like "I didn't know" or "there was no contact information for licensing."

When it comes to contracts, contracts can be valid if both sides give a coherent expression of their will to enter the contract. The validity would become a question if one side challenges the contract afterward, claiming error or deception. Unless there are very good reasons for using non-standard dates, the deception claim should get good hearing in court. (Certain types of contract, like real estate, must be certified by a notary who might refuse to sign if he or she is confused.)

  • For copyright, not just Europe - every country signatory to the Berne Convention
    – Dale M
    May 2 at 21:29

This is probably based on contract law, where the importance is that it is not ambiguous (Date format or calendar type).

This article states that 'Gregorian' is sometimes found after the year to avoid possible confusion with Hebrew or Islamic dates. Referring to the Gregorian Calendar? - Adams on Contract Drafting.

So Copyright (c) 2774 AUC <OWNER> would probably also be valid, even if its usage defeats the main purpose of making the date of publication clear to anyone reading the copyright notice.

  • 1
    I typed 2774 AUC into Google and it told me it means "Ab Urbe Condita" or "From The Founding Of The City". It refers to the year of the founding of Rome, which was the Epoch used in Ancient Rome. And it is 2021 AD. If there was a legal question whether it was clear enough, is something that Google tells you instantly clear enough?
    – gnasher729
    May 3 at 16:37
  • 1
    @gnasher729 You have just proven the point. If it had been instantly clear to you, there would have been no need to search for it in Google in the first place. That the meaning can be swiftly found shows also that it is never the less not ambiguous. Ab urbe condita was, however, not used in ancient Rome but only later. May 3 at 19:48
  • But the question is: Does it have to be instantly clear? I bet there are people who don't know what AD means. (And it's not ambiguous. It's not common knowledge but it's not ambiguous. 10/5/11 is ambiguous. )
    – gnasher729
    May 4 at 21:47
  • @gnasher729 The Copyright Act of 1909, §18 states only: the notice shall include also the year in which the copyright was secured by publication.. If you wish to be user unfriendly, feel free to do so. Through the usage of the epoch, the date is not ambiguous. With only '2774' or '12021' it would be ambiguous. May 5 at 3:38

Depends on the jurisdiction. For example, in Israel, dates on "every official letter in the Hebrew language sent by a public authority" must be according to the Hebrew calendar (source). So, at least when dealing with state institutions, the Hebrew date would be the binding one (at least from their side).

(Of course, in day to day life, Israel lives by the Gregorian calendar)

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