Deferential speech style is the most polite and formal speech style.

It is used mostly in formal communication settings:

• Broadcasting: see a TV news broadcasting script and clip
  
• Public speech
  
• Business-related meetings including interviews and conferences
  
• Speaking to a highly respected person:
  
  • Among family members, the Polite Style ~어요/아요 is likely to be used. In some extremely conservative families, the children may be encouraged to use the Deferential Style to parents and grandparents.
    
• First time encoutner: see a TV drama script and a movie clip
  
  • 안녕하십니까?
  • 저는 . . . -(이)라고 합니다.
    
• Formulaic/fixed expressions:

• 처음 뵙겠습니다. 만나서 반갑습니다.
• 잘 부탁합니다.
• 잘 먹겠습니다.
• 학교에 다녀오겠습니다.
• 수업 시작하겠습니다.
• 축하합니다.

Polite Style vs. Deferential Style