In business, COB almost always means “Close of Business” —the end of the standard working day, often around 5:00–6:00 p.m. local time.

What “COB” Means in Business

When you see “COB” in an email or document, it usually signals a deadline tied to office closing time , not midnight.

Typical uses:

  • “Please send the report by COB today.” → Send it before the workday ends.
  • “Payment must be received by COB Friday.” → Funds should arrive before the bank’s business day closes.

COB helps teams align around a specific business-hours cutoff instead of a vague “end of day.”

Common Contexts Where You’ll See COB

  • Corporate/office work : For reports, approvals, and project updates that need to be done during working hours.
  • Banking and finance : For transaction cutoffs, settlements, and daily reconciliations.
  • Contracts & legal docs: To set clear daily deadlines in agreements.

A quick example:

“Could you approve the budget by COB today so we can launch the campaign tomorrow?”

COB vs EOD (and Similar Terms)

People often confuse COB with EOD, but there’s a subtle difference in how many professionals use them.

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Term Typical Meaning When It’s Used
COB Close of Business (end of office hours, e.g., 5–6 p.m. local time). Office-based work, banking, finance, and corporate deadlines that must be done during the workday.
EOD End of Day (can mean end of calendar day, sometimes as late as midnight). More flexible or remote/IT work when tasks can be finished outside office hours.
EOB End of Business (usually same idea as COB). Alternative phrasing to COB, often interchangeable.
COP Close of Play (often UK usage, originally from sports; similar to COB). Some UK or Commonwealth business contexts for “today’s business-hours cutoff.”
Because interpretations vary, many teams now **add a clear time and time zone** , like “by COB today (5:00 p.m. EST).”

Other Meanings of COB (Outside Pure Business Context)

Occasionally you might see COB used with different meanings depending on the field:

  • Medical insurance : “Coordination of Benefits” (how multiple insurers share payment responsibility).
  • Electronics : “Chip On Board,” a packaging technology for integrated circuits.

In everyday business email, though, if someone says “by COB,” they almost always mean “by the end of the business day.”

TL;DR: In business, COB = Close of Business —a deadline by the end of the working day, typically around 5–6 p.m. in the relevant time zone, used to make deadlines clear and aligned to office hours.

Information gathered from public forums or data available on the internet and portrayed here.