Writing the Date Formally for Business, Invitations, and Academic Work
In formal U.S. writings, you never want to omit the year or use a purely numerical form for the date. For example, if you were to write a formal business letter, you’d write out the entire date, including the full month (January 1, 2011). Writing it out in such a way allows the notation to be understood by everyone.
In formal European writings, the date is typically written in a similar fashion to the American version. So July 4, 2011 would simply have the month and day switched around, making it 4 July 2011. Notice in a formal European version of the date, there’s no comma. The comma separating the date from the year is an Americanism that the Europeans do not follow.
