The employer usually informs Revenue of the new employee but the employee can do it also if they have the employer's tax reference number.
It is 100% the employees responsibility to inform the revenue.
Really.
I was under the impression that if the employee does nothing the employer just deducts tax under the emergency rules and this situation would continue until the employee contacted revenue to apply for a cert.
What is supposed to happen when the employer informs revenue of a new employee? Do they contact the employee?
Just asking as in my experience with PAYE you stayed on ET until you contacted revenue yourself. I have never known an employer to take the initiative.