The IRS recently issued Notice 2018-95 to provide transition relief to 403(b) plans that erroneously excluded part-time employees from eligibility to make elective deferrals when the employees should have been eligible to participate under the “once-in-always-in” requirement (“OIAI”). Under the OIAI requirement, once an employee is eligible to make elective deferrals, the employee may not be excluded from eligibility for making elective deferrals in any later year on the basis that the employee is a part-time employee. The IRS issued Notice 2018-95 to provide transition relief because many employers that sponsored 403(b) plans did not realize that the OIAI requirement applied to the part-time exclusion.