Thursday, May 1, 2008

Terminology - Earliest Known Use

The term earliest known use, or EKU, is the first date on which a stamp is used. In a perfect world, the earliest known use of a stamp is the same as its first day of issue (FDI). However, the world is not perfect and there are several reasons why the two dates may not be the same. But first, a little explanation of what it takes to be a collectible EKU stamp.

Most, but not all, earliest known use stamps require these components in order to be considered a true EKU:

  • It must be postally used. As such, it cannot have been favor-canceled whereby a postal authority legitimately, or illegitimately, dated the stamp without it going through the mailstream. It would be too easy for an unscrupulous postal clerk to cancel a sheet or two of stamps and sell them as EKU stamps. Ideally, EKU stamps would go through the mail to their intended destination.

  • By definition it requires that a date of cancellation appear on the stamp and/or the cover to which it might be attached. Without a valid postmark, there is no way to prove when the stamp actually went through the mailstream.

  • If the cancel date is not on the stamp, the stamp must be tied to the envelope by the cancellation. If the date is not completely visible on the stamp itself, the stamp must appear on an envelope or postal card where the cancellation clearly ties the stamp to the cover. Without this requirement, a stamp could have just been stuck to an older cover and appear to be issued earlier. The cancellation is what validates the date the stamp as used.

There are a couple of reasons why an earliest known use of a stamp can occur before the first day of issue for the stamp:
  • Accidental causes. This is probably the most likely cause of most EKUs. Postal authorities get stamps in advance and sometimes clerks just forget and sell the stamp over the counter before it is officially released. With thousands of post offices in a country, it can easily happen.

  • Illegal activities. If sheets of stamps are stolen or slipped out the back door of the post office, and used prior to the first day of issue, these stamps can become earliest known uses. Also, an unscrupulous postal clerk could theoretically backdate a cancel and create EKUs at will.

Also, there are a few reasons why an earliest known issue for a stamp can occur after a first day of issue for a stamp:
  • Changes to stamp formats. If a postal authority releases a variation of a stamp that creates a new type, with a perforation change, for example, the earliest known issue for that variety would be different than the original first day of issue.

  • Losses of early issues. For older stamps, the earliest known use of a stamp may be after its official issue date because there are few copies that exist. Early issues may not have been collected on-cover, and thus there are few examples.

  • Lack of demand. If there is no demand for a stamp's first day of issue, the earliest known use can occur later. This would probably only occur on expensive or unusual denominations on stamps issued in small quantities by remote countries.

Searching for earliest known uses of stamps can be an interesting aspect of philately. Be prepared to look through lots of covers if you ever hope to find an EKU.

Previous Terminology Topics:


Anonymous said...

There is another possibility, there never was an official first day of issue. PO used stamps as they were received. This seemed to have occurred with some early Australian and Aust. Colony issues.

Tony Servies said...

Point well made.

Thanks for the insight.


Rob Hardy said...

I don't know anything about stamp collecting. Today, 28 August 2009, I bought a sheet of EID stamps, and looking them up on the website of the Post Office, I see that there is a first day of issue 23 September. Is there anything I ought to do with these? Would a collector be interested in my using them on envelopes mailed to myself or to the collector?

Rob Hardy
robhardy1 at

Tony Servies said...


EID stamps have been produced for a number of years using the same basic design. The stamps have different denominations on them, depending on the first class rate in the year in which they are being offered.

From something I read in a recent Linn's stamp article, the EID stamp is being re-designed/re-issued. I believe this is the Sept. 23rd date of which you speak. My best guess is that the EID stamps you purchased are the current design, and not the design due out Sept. 23rd.

You might want to go to the USPS web site ( and visit their stamp store. See if the design of your stamps exactly matches the ones due Sept 23rd. If not, I would tend to think they are the current issue.

Rob Hardy said...

You may well be right. On closer examination, I cannot find, however, this stamp on the Post Office website, not even as an upcoming release. It is a 44 cent stamp, so surely it's this year's.

The postmistress at the little town I got them from pulled them out of an envelope that had just been mailed to her, one that she opened in front of me, so I suspect they are new.


Tony Servies said...

If they are new, the only proof that they were issued early is to get them postmarked. You could create some letters, use the stamps, and then mail them. That would serve as documented proof as an Earliest Known Issue.

Tony Servies said...


After further research, I do believe you received stamps prior to their first day of issue. The USPS's "New Stamp Issues - 2009" publication indicates that the 44-cent EID stamp will be issued on Sept. 3rd (note, not Sept. 23rd as listed in your initial post). This would explain why your post office staff received them in an envelope about a week ago. You might want to send a few of them on an envelope to yourself, strictly for the novelty of it. But you must do it ASAP ... after Sept. 3rd, you will have no proof that you purchased them prior to their official first day of issue. By the way, EKU stamps for modern day issues, are not particularly valuable, as this happens with some frequency. But it clearly will be of interest to EKU collectors, and it is obviously a conversation piece.

If you have an opportunity to put one of the stamps on an empty envelope, and mail it to me prior to Sept 3rd, I would appreciate it. You can find my address on the right side of the page under the heading "How You Can Help".