Needn't Have (english grammar)

• Needn't Have

• 
• Use needn’t have when an action was completed, but the action was unnecessary or a waste of time.

  
  

  subject + needn’t have + past participle

  
  

  -Jill needn’t have stopped at the ATM for cash.  The restaurant accepts credit cards.

  (The speaker believes that Jill's action was unnecessary.) 

• They needn't have bought a second car. They don't drive very often.	You needn't have gotten a loan from the bank.  I would have given you the money.
  We needn't have ordered more food. We had so many leftovers.	Emily needn't have used a safety deposit box. Her money would have been safe in her account.

 Source : Alison