You probably saw this but per the EOB. A 4% minimum would, in my mind, not follow the guidance.
Minimum deferral rate and minimum increments permitted. Q&A-3 of IRS Notice 2000-3 permits safe harbor 401k plans to require salary reduction elections to be in whole dollar amounts or in whole percentages of compensation. Section V.B.1.c.ii. of IRS Notice 98-52 stated that a safe harbor 401(k) plan could set a maximum limit on elective deferrals, so long as an employee's ability to get the maximum match available under the plan was not compromised, but had to permit the employee to elect to contribute "any lesser amount." The ability to require whole dollar amounts or whole percentages is a reasonable compromise. Thus, a minimum elective deferral rate of 1% of compensation could be required by a safe harbor 401(k) plan. The regulations adopt the Notice 2000-3 approach as well. See Treas. Reg. §§1.401(k)-3(c)(6)(iii) and 1.401(m)-3(d)(6)(iii).