Automatic Enrollment Opt-Out

I have a plan that was not designed in a manner that works well for the business.  Eligibility is immediate and 95% of employees are seasonal/part-time and in college.

Regarding automatic enrollment in 2025, can the sponsor use the employee's initial opt-out from when they were hired as an election to defer 0%?  Or does there need to be a formal (in writing) opt-out following the EACA notice that was distributed?

Those would be prior to implementation of the EACA, so I am going to say no. Yes there needs to be a new opt out.  And I would personally absolutely consider changing eligibility.