There is no one “official” format, but here are some basic rules to keep in mind when composing a cover letter:
A three line block in the top right hand or left hand corner of the page containing: your home street address; city, state and ZIP code; and the date. (The date may be separated from the block by one line.)
Another three line block, flush left, one space below the date and one space above the greeting. This block contains the addressee’s full name and address, including city, state and ZIP code.
Use a colon after the greeting, not a comma. The greeting should address a specific person in a formal manner. “Dear Ms. Harper:” is perfect; “Dear Jennifer:” is not.
Use a personalized salutation (not, for example, “To Whom It May Concern”). Make an effort to find out who will be receiving your letter. If necessary, telephone the company and ask. If you do not find a specific name, address the letter to “Hiring Manager,” “Human Resources Manager,” or simply “Manager.”
Paragraphs should be separated by a line of space; indentation is not necessary.
You may use bullets and bold print in the body of your cover letter to organize and highlight information, and make it easier to read. If you do decide to use them, do so conservatively.
The closing should read “Sincerely,” followed by your signature underneath, then your full name in print underneath that. Always leave enough room for your signature between the closing and your name when you print your cover letter.