Q. “[Name of organization] wishes a Happy 75th Birthday to [name of person].” Is this correct? What are the rules of capitalization for “Happy Birthday”?
A. The rules are that common adjectives and nouns should be lowercased and names of holidays are uppercased. Although birthday is not the name of a holiday, people often cap “Happy Birthday” in cards and notes to make it look festive. For this reason, worrying about correctness in such contexts can be counterproductive.