When Your COB Is My EOD

The other day in a business writing class, I read an abbreviation that perplexed me. Here is the sentence:

We need your contributions by the COB on December 14.

The writer, Linda, was asking for contributions for an adopt-a-family holiday program. Do you recognize COB? I strained my brain to think of what it might be, but I could not come up with anything.

Linda was surprised by my ignorance. She thought everyone would recognize COB as "close of business," as in the close of the business day. But I know the close of the business day as EOD, "end of day."

Linda countered that everyone in her organization uses COB, so the employees, her readers, will have no difficulty understanding her message. Or will they? A coworker pointed out that COB has another meaning in their organization: California-Oregon border.

I wondered for a moment whether any employees might leave their contributions by the California-Oregon border. I have to admit that is extremely unlikely, but the potential for confusion still exists.

Linda agreed and simplified her sentence:

We need your contributions by noon on December 14.

That approach will work fine as long as her readers are in the same time zone.

Take a moment to check your writing for abbreviations and acronyms. Will your readers know that DC is the distribution center, or will they be thinking of the District of Columbia, discount code, or Divorce Court? Make it easy for them. Spell it out.



  1. I found your article because … wait for it … COB was in a communication from a colleague in our company and I had no idea what it represented. Interesting in your example, the two would mean the same, but EOD might also be midnight (time zone issues aside), and that the correction inserted an entirely different submission point (unless business closes at noon).

  2. Typically, COB would be by 5pm and EOD before, well technically midnight, but basically to convey to the other person to expect the report/file/whatever the next morning. Both when used refer to the time zone in which the user of the abbreviation is (unless specified otherwise)

  3. Hi Lynn,

    I found your article by searching “COB vs EOD” just before sending out an email. To confuse things even further, the person I’m writing previously used “EOB”. I certainly knew they meant “End of Business” but I wanted to stick with “COB” since I used it exclusively during 9 years in the USAF (where acronyms were a way of life!). Thanks for your article!

  4. I found this while looking for a reason why anybody in their right mind would use EOB. COB is a more useful acronym because it can be pronounced like a word, Phonetically.
    IE:”I need your proposal by cob wednesday.”
    “I need your proposal by eeeahb?”
    If you are composing business correspondence, you should have the intellect to decipher COB from the context of the message. You already knew that eOB was end OF BUSINESS. What possibly could COB mean?! Oh my, I’m so frazzled. Get Real.

  5. That’s funny! I have heard COB for years and years and only just encountered EOD for the first time this week. I just searched on these terms to confirm whether EOD meant the same as COB (actually, I was hoping it was midnight!)

  6. I’ve always used and have experienced others using EOD…until today. Your article came up in my search as I racked my brain on what COB meant. Perhaps COB vs. EOD popularity is determined by region within the U.S.? I’m in the Southwestern part of the country.

  7. This is a clear message:
    Please deliver the purchase offer by 17.00 Los Angeles time on Friday 12 November 2013.

    Unless it is an internal memo within the same company, this is an obscure message:
    PLS deliver your PO by COB 11/12

  8. There you go. I was perfectly familiar with COB, but found your blog when I was wondering what my European colleagues meant by EOD.

    However, if I stay back to work on something, my ‘EOD’ is when I finish, or midnight, whichever comes first.

  9. COB also can stand for “Continuity of Business” that ensures critical business functions continue to exist as normal, often used in business disaster recovery planning.


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