"Beginning with taxable years starting on or after January 1, 2024, ... catch-up contributions for 'higher-paid participants' must be made as Roth contributions.... This new rule introduces a new definition of compensation and a new group of participants for recordkeepers to track, which will significantly complicate plan administration.... Plan sponsors who allow catch-up contributions but have resisted adding Roth deferrals may face a difficult decision -- either stop allowing any catch-up contributions beginning in 2024 or add Roth deferrals to the plan."