A Proofreader’s Guide to Dates in AP Style

The Associated Press Stylebook is the go-to style guide for many writers, news outlets, and businesses. And if your clients use AP style, you’ll need to know how it works. With that in mind, here we’ll look at what proofreaders should know about dates in AP style, including:

• The basic date format (and when you might need to adapt it).
• Guidelines on when and where to include commas in dates.
• When, how, and where months and days should be abbreviated.
• Advice about using “on” before dates (and when to omit it).
• When to include an apostrophe in decades.
• What AP style has to say about starting a sentence with a year.

This will help you know what to look for when proofreading documents that contain dates. For more information on all the above in AP style, read our guide below.

Rules for Writing Dates in AP Style

The AP Stylebook has two key rules that will apply to most dates:

1. Dates should be written with Arabic numerals, not words.
2. Do not use ordinal indicators after dates.

You can see how standard AP-style dates would look below (plus some incorrect versions):

Goodliffe was born May 5, 1981. ✔

Goodliffe was born May fifth 1981. ✘

Goodliffe was born May 5th, 1981. ✘

If you see a date written as words or with ordinal suffixes, then, it will need correcting.

In addition, AP style suggests leaving out the year in stories that refer to the current year. For example, an article from 2021 that referred to something in 2021 would say:

The week-long event began May 28. ✔

The assumption is that the reader will know it refers to the current year, which is fine for most news stories. However, if your client refers to something from a year other than the current year, or if the year in question could be unclear, you should advise them to add one.

Regional Date Formats

You’ll notice we’ve used the US date format in the examples above. This is because The AP Stylebook focuses on US English, and all the examples it gives use this format.

However, the “correct” format to use will depend on your client’s chosen dialect. You may even need to advise your client to adapt the date format in some cases (e.g., suggesting switching to the UK format if the document is aimed at a UK audience).

We’ll note any further differences between US and UK dates as relevant below.

Commas in Dates

There are two situations in which AP style suggests adding a comma in a date. The first is between the date and the year when using the US date format:

The event is scheduled for June 5, 2021. ✔

The event is scheduled for June 5 2021. ✘

However, other date formats have the month between these numerals, so no comma is required. For instance, a client using the UK date format would write “5 June 2021.”

The other is between the day and the date when including the day of the week:

The event is scheduled for Saturday, 15 Aug. 2021. ✔

The event is scheduled for Saturday 15 Aug. 2021. ✘

This applies regardless of the date format (e.g., in both UK and US-style dates).

Abbreviating Months and Days

When dates are used in the main text of a document, AP style suggests abbreviating months longer that are more than five letters long (i.e., Jan., Feb., Aug., Sept., Oct., Nov., Dec.):

24 Nov. 2009 ✔

6 June 1984 ✔

24 November 2009 ✘

6 Jun. 1984 ✘

Keep an eye out for these abbreviations, plus the full stop at the end, when checking documents with dates. However, months without an exact date should not be abbreviated:

In Britain, snow is more common in February than in December. ✔

We can trace this phenomenon to January 2006. ✔

In Britain, snow is more common in Feb. than in Dec. ✘

We can trace this phenomenon to Jan. 2006. ✘

In addition, the rules are different in tabular material. In a table, all months can be abbreviated to their first three letters without a full stop (e.g., Jan, Feb, Mar, Apr). The same applies to days of the week (e.g., Mon, Tue, Wed). However, days of the week should always be written out in full if they appear in the main text of an AP-style document.

Using ‘On’ Before Dates

Typically, AP style suggests omitting the word “on” before a day or date:

They are set to reconvene Monday. ✔

They are set to reconvene on Monday. ✘

The two exceptions to this are when a date falls at the start of a sentence:

On 23 March, the park will open to the public. ✔

23 March, the park will open to the public. ✘

And when adding “on” will help to prevent ambiguity, such as when a day of the week follows a proper noun. For example, “on” between the company name and date for clarity:

A new CEO will join Proofreading Solutions on Monday. ✔

A new CEO will join Proofreading Solutions Monday. ✘

Keep in mind, though, that this omission of “on” is quite distinctive of news writing, especially in American English. Whether to do so may thus be a matter of stylistic preference for your client, depending on what they are writing and the dialect they’re using.

Apostrophes in Decades

AP style suggests using an apostrophe before numerals when abbreviating a decade:

Queen’s career spanned the ’70s and ’80s. ✔

Queen’s career spanned the 70s and 80s. ✘

Keep an eye out for apostrophes being wrongly used to indicate a plural, too (e.g., 1800’s).

Starting Sentences with Years

Most style guides suggest not using numerals at the start of a sentence, but AP style makes an exception for years. As such, a sentence can start with a year:

2020 was a difficult year for many people. ✔

When proofreading, there would thus be no need to correct or rephrase this.

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