Online application, followed by a phone interview, an assessment centre and a final partner interview.
The online application is similar to the rest of the Big 4: a situational judgement test and some basic maths questions.
The phone interview is outsourced, so they follow a script and do not ask any follow up questions so make sure you say everything you want to before they ask the next question.
The assessment centre is split into two parts: a group task and a written task. The group task is about EY's values and is more about how you work rather than the answers you give. Basically just make sure you contribute, definitely don't interrupt anyone. A good way to assert yourself and impress the assessors is to volunteer to keep time before you begin the task.
The written task was essentially an e-tray exercise: you have to write a couple of emails, and some reports. There is a bit of maths, so make sure you brush up on the basics like percentage changes. It is quite tight on time so make sure you at least put something down for each task.