# COB Full Form: Close of Business (Meaning at Work)

> COB stands for "close of business": the end of normal office hours, usually 5 or 6 pm, used as a deadline.

- **Term:** COB
- **Full form:** Close of Business
- **Part of speech:** abbreviation
- **Pronunciation:** /ˌsiː oʊ ˈbiː/
- **English level (CEFR):** B1
- **Register:** Formal, Written
- **Region:** US and UK
- **Topic:** [Agile and project terms](https://app.speaktechenglish.com/learn/topics/agile-project-management-terms.md)
- **Lesson:** https://app.speaktechenglish.com/learn/cob
- **Last updated:** 2026-10-27

## Meaning

COB stands for "close of business": the end of normal office hours, usually 5 or 6 pm, used as a deadline.

COB is common in finance, consulting, government and formal email: "Please confirm by COB Thursday." It means the same as EOD for most people, but sounds slightly more formal. Like EOD, it depends on location, so international teams often add a city or time zone: "COB London time". You may also see "COB today" and "by COB".

## When you hear it

A client email says: "We need your signed contract by COB Friday."

## Examples

- **in a client email:** "Could you return the signed agreement by COB Friday?"
- **in a finance team message:** "All expense reports are due by COB on the 25th."
- **in a project update:** "Legal will share their comments by COB tomorrow."

## What native speakers say

- "Please confirm by COB today."
- "We'll send the revised quote by COB Thursday."
- "COB London time, please."

## Common mistakes

- ✗ "I'll reply until COB." → ✓ "I'll reply by COB." (Use "by" with deadlines.)
- ✗ "COB means midnight." → ✓ "COB means the end of office hours, around 5 to 6 pm." (Business closes at the end of the working day, not at midnight.)
- ✗ "Please send by COB. (to teams in New York and Bangalore)" → ✓ "Please send by COB New York time (5 pm ET)." (COB is local. Name the location or time zone.)

## Be careful

COB is local time by default. Name the time zone when your team or client is in another region.

## Word forms

| Part of speech | Word | Example |
| --- | --- | --- |
| full form | close of business | Please reply by close of business on Friday. |
| with a day | COB Thursday | The window closes COB Thursday. |


## Collocations

- **by COB**: the usual deadline phrase
- **COB today**: today's end of office hours
- **COB + city / time zone**: makes the deadline clear for global teams

## Synonyms

- **EOD (end of day)**: almost the same, a little more casual
- **end of business day**: full, formal phrase
- **by 5 pm**: the clearest option

## Opposites

- start of business
- first thing in the morning

## Practice

This lesson has 4 practice exercises with instant feedback on the page: https://app.speaktechenglish.com/learn/cob

## FAQ

### What is the full form of COB?

COB stands for "close of business".

### What time is COB?

The end of normal office hours where the sender works, usually 5 or 6 pm.

### Is COB the same as EOD?

Almost. Both mean the end of the working day. COB sounds more formal and is more common in finance, legal and government.

### What does COB mean in banking?

In banking, COB often means the end of the processing day: payments after this time are handled the next business day.


## Related

- [deadline](https://app.speaktechenglish.com/learn/deadline.md)
- [sign-off](https://app.speaktechenglish.com/learn/sign-off.md)
- [escalate](https://app.speaktechenglish.com/learn/escalate.md)
- Full glossary: https://app.speaktechenglish.com/learn.md
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