A US woman will be charged with causing the death by dangerous driving of teenage motorcyclist Harry Dunn.
Mr Dunn, 19, died in a road crash in Northamptonshire in August that led to suspect Anne Sacoolas leaving for the US under diplomatic immunity.
The Crown Prosecution Service (CPS) confirmed it had started extradition proceedings through the Home Office.
Mr Dunn died after his motorbike was in collision with a car owned by Mrs Sacoolas outside RAF Croughton.
The RAF base was where Mrs Sacoolas’s husband Jonathan worked as an intelligence officer.
The CPS said immunity did not apply to dependants of consular officials outside of London.
Mrs Sacoolas, 42, left the UK and returned to her native US, claiming diplomatic immunity.
The Foreign Secretary Dominic Raab said a review into the immunity arrangements at Croughton for US personnel and their families had concluded.
It found that it was an “anomaly” that family members had “greater protection from UK criminal jurisdiction than the officers themselves”.
Chief Crown Prosecutor Janine Smith said it had authorised Northamptonshire Police to charge Mrs Sacoolas.
She said the director of public prosecutions had met Mr Dunn’s family to explain the decision.
Mr Dunn’s parents Tim Dunn and Charlotte Charles had previously been critical of the lack of communication from the CPS.
A Northamptonshire Police spokeswoman said the force “welcomes the charging decision from the CPS”.
A previous statement issued on behalf of Mrs Sacoolas said she was “devastated by this tragic accident.”
“No loss compares to the death of a child and Anne extends her deepest sympathy to Harry Dunn’s family.”
It added she had “fully co-operated with the police”.
Mr Dunn’s parents rejected a “bombshell” offer from Donald Trump to meet Mrs Sacoolas at the White House in October.
They said they had felt “a little ambushed” when the president revealed she was in the next room.