Commas in dates are one of those punctuation details that feel obvious until you actually need to apply them. Do you write January 14, 2026 or January 14 2026? What about Monday, January 14? And once you add a year after the day, does the comma stop there or carry on through the sentence? The rules are consistent once you see the logic, and this guide lays them out clearly.
The standard American date format: month, day, year
In American English, the most common date format lists the month first, then the day, then the year: January 14, 2026. That comma between the day and the year is required. Skip it and the date reads as a string of unbroken numbers.
The trickier rule comes after the year. When a full month-day-year date appears in the middle of a sentence, the year needs a comma after it too. Both commas work as a pair, bracketing the year the way parentheses would.
Correct: The contract was signed on January 14, 2026, and took effect immediately.
Incorrect: The contract was signed on January 14, 2026 and took effect immediately.
Dropping that second comma is the most common date-punctuation error in business writing. The year is treated as parenthetical information, so it opens with a comma and closes with one. Both or neither.
When no comma is needed: day-month-year format
The day-month-year order, standard in British English and international business writing, drops the comma entirely. You'd write 14 January 2026 with no comma anywhere. Because the day number and year don't sit next to each other, there's no ambiguity and no comma required.
This matters in practice. A British colleague writing 14 January 2026 isn't making an error. The format itself removes the need for the comma. If your organisation uses international date formats, check which convention your style guide follows before editing someone else's work.
Adding the day of the week
When you add a weekday at the front, place a comma after it. This applies whether or not a year follows.
- Monday, January 14
- Monday, January 14, 2026
- Monday, 14 January 2026 (no second comma in this format)
The comma after the weekday separates it from the date that follows. When the full month-day-year date sits mid-sentence, the same bracketing rule applies: The meeting falls on Monday, January 14, 2026, so plan accordingly. Three commas in one date reference looks like a lot, but each one earns its place.
Dates with only a month and year
No comma belongs between a month and a year when no day appears. January 2026 is correct. January, 2026 is not.
This rule catches many writers off guard. The comma between the day and year exists to separate two numbers that would otherwise merge. Remove the day number and the reason for the comma disappears with it. The report was published in January 2026 is clean and correct.
Ordinal numbers in dates: "th," "st," "rd," and "nd"
Ordinal suffixes like 14th, 1st, or 3rd belong in informal or ceremonial writing but not in standard business documents. If you do use them, the comma rules stay the same: January 14th, 2026 still takes the closing comma mid-sentence. For more on how these ordinal forms work in holiday and event writing, see the piece on Thanksgiving "th": how to write it correctly every time.
Numeric date formats
Fully numeric dates, like 01/14/2026 or 14/01/2026, use slashes or hyphens rather than commas. No commas appear inside numeric date formats. The ambiguity between American (month/day/year) and international (day/month/year) formats is exactly why many style guides, including The Chicago Manual of Style, recommend spelling out the month in formal business documents.
ISO 8601, the international standard used in technical writing and data systems, formats dates as YYYY-MM-DD with hyphens and no commas at all. 2026-01-14 is unambiguous in any country, which is why it dominates in contracts with international parties and in software documentation.
Quick reference: comma rules by format
The patterns below cover the formats you'll encounter in most business writing:
- Month Day, Year (mid-sentence): comma after day, comma after year. The deadline is March 3, 2026, for all submissions.
- Month Day, Year (end of sentence): comma after day, period after year. The deadline is March 3, 2026.
- Day Month Year: no commas. The deadline is 3 March 2026.
- Weekday, Month Day: comma after weekday only. The meeting is Thursday, March 3.
- Weekday, Month Day, Year (mid-sentence): comma after weekday, after day, and after year. The meeting is Thursday, March 3, 2026, at 10 AM.
- Month Year: no comma. The report covers January 2026.
Commas in dates and the rest of your punctuation
Date commas interact with other punctuation in sentences, and that's where writers get tangled. Consider a sentence that already has a conjunction: The project launched on April 1, 2026, and the team celebrated. Both date commas stay. The conjunction's comma doesn't replace the closing comma on the year.
For a deeper look at how commas work before conjunctions like "and" and "but," the guide on using a comma before and after "but" covers the full logic, which applies to dates in the same way.
Time formats follow a parallel set of rules. If you're writing both a date and a time in the same sentence, spell both out clearly and let each element's punctuation do its own job. The AM/PM question alone has its own set of conventions worth knowing about.
The one test worth doing
When you're unsure whether a comma belongs after the year, read the sentence aloud and pause at each comma. If the sentence sounds complete and natural at each pause, the commas are placed correctly. If a pause sounds wrong, either add or remove the comma and read it again. Trust the pause. It reflects the same bracketing logic that governs date punctuation.
Getting commas in dates right is a small detail, but in contracts, reports, and formal correspondence, small punctuation errors carry outsized weight. A date with a missing comma looks like carelessness. With the rules above, you won't need to guess again.