Comma after the year

Many writers are unsure whether to put a comma after the year when writing the date.

Use of a comma depends on how you write the date.

When you write the date out in full using the recommended month-day-year sequence, put a comma both before and after the year:

• The workshop on April 23, 2009, was well attended.
• Friday, March 27, 2009, was the original date for the workshop.

NOTE: Of course, you do not need a comma after the year if the sentence requires another mark of punctuation, as in the example below:

• We planned to finish the project by January 8, 2009; however, we completed the work on December 15, 2008.

When you write the date using the day-month-year sequence, do not use any commas:

• The letter dated 29 January 2007 is missing from the file.

When you write only the month and the year, do not use any commas:

• He worked in my department from May 2001 until October 2003.