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COB vs EOD Explained: How To Use These Business Acronyms

Learn what the acronyms COB and EOD mean and how to use them in the business world

COB and EOD are very commonly used terms to communicate deadlines, appointments, and project timelines. This makes it essential to know what each acronym means and how to use it.

These acronyms are often used interchangeably at the workplace but have slightly different meanings. We’ll dive into what each abbreviation stands for and give tips on using them effectively in written business communications like professional emails.

Six essential business communication terms defined

First, let’s define a few common terms many will encounter daily in the business world.

  • Business days: The working days when most businesses are operating, excluding weekends and public holidays.
  • Business hours: These are usually 9 am to 5 pm on business days
  • Time zones: This refers to a geographic region which uses the same standard time.
  • Public holiday: A national holiday observed by the citizens of a country
  • Bank holiday: This term originates from the United Kingdom and is used for a day when banks close. It is not always observed as a public holiday.
  • Financial markets: A marketplace where people trade financial instruments like bonds, equities and stocks.

What is close of business (COB)?

COB refers to the end of the business day according to the Eastern Standard Time (EST) in the United States, usually 5 pm EST. COB also describes when financial markets close for trading in New York City.

When someone uses COB to refer to a deadline, it generally means 5 pm EST for that specified day. Unless you’re working in the EST time zone, the term does not denote the end of the business day according to your local time. If you’re using Greenwich Mean Time (GMT), which is 5 hours ahead of EST, COB means 10 pm GMT.

Here’s how to use close of business (COB) in a sentence:

“Can you send me October’s investor report by COB today?”

Here's how to use close of business (COB) in a sentence:

 “Can you send me October’s investor report by COB today?”

EOD stands for the end of the business day according to the sender’s time zone. Suppose a client requests a deliverable by EOD. In that case, most companies expect you to deliver by the end of the business day according to their time zone unless specified otherwise.

Here's how to use end of day (EOD) in a sentence:

“I need your slides in by Tuesday EOD please.”

Guideline #1: Use COB to set a deadline with someone in the EST time zone

Since COB stands for 5 pm EST, COB is more likely to be understood by people in the EST region since everyone works in the same time zone. Here’s how you might use COB in an email to ask a colleague for a report:

Hi John,

Great job on the presentation at our last client meeting. Could you send me the quarterly marketing report by Friday, 22 January, COB?

Best regards,


Other COB usage examples:

  • As applications close by 5 pm EST on Tuesday, I need your details by COB today.
  • Let us know your mailing address by COB Monday so we can send you the documents during working hours.

Guideline #2: Use COB when communicating with clients or team members working remotely in a different time zone

If you’re working with a client who hasn’t specified a deadline and is in a different time zone, it’s good practice to give a clear deadline for delivering your product or service. COB works better here as the recipient can convert the deadline to 5 pm EST according to their time zone.

COB usage example:

  • I’ll get you the first draft of your design by Thursday COB.

Guideline #3: Use EOD for a client with a deadline in their time zone or if you share the same time zone

Using EOD is handy if you need to communicate a deadline or manage a client’s expectations quickly. Following are some usage examples.

  • I’ll get you November’s financial figures by Monday EOD.
  • We’re aiming to get our campaign live by Wednesday EOD.

Guideline #4: Use EOD when assigning or communicating deadlines to team members

EOD is a quick and effective way to communicate a deadline to team members without lengthy emails. Sentences like “Could you get me the final dataset by Tuesday EOD, please” communicate a deadline clearly and professionally.

Tried-and-tested tips to ensure correct communication

Although different companies might have their own best practices, we have found that these tips work well in accurately conveying deadlines.

Specify the exact date, time and day you mean in brackets next to COB or EOD

When communicating with someone new or across different time zones, specify the exact time and time zone you’re referring to with your acronym of choice.

Hi John,

Great job on the presentation at our last client meeting. Could you send me the quarterly marketing report by Friday, 22 January COB (17:00 EST?)

Best regards,


Ask the recipient to clarify the exact time

To confirm a deadline or an appointment, ask your email recipient for the exact time they’re referring to. Remember to maintain email etiquette by sounding friendly and polite but not too casual.

Hi Jane,

Thank you for your email. Looking forward to speaking with your company next week.

Could you clarify if you mean Friday 5 pm EST when you say Friday COB?

Best regards,


Better working relationships start with clear communication

Today’s business environment spans multiple time zones and different countries, and communicating well is essential to avoid confusion.

Improving your communication skills can help you land a new client, connect with existing clients or exceed expectations on a high-stakes project. Refer to this guide if you’re unsure how to use these different acronyms with your clients or within your company.

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