I am using the words pro bono in a letter addressed to my line manager using MS Word. My query is: does pro bono needs to be typed using italics format?
There is no right or wrong in this. In many cases, the use of italics for such latinisms is merely a matter of editorial decision. Similarly, you may make your own decision. What matters most is that, having decided on your style, you adhere to it and do not swing from one to the other in the same communication.