I am working on a 401(k) / New Comp Plan and and need to increase the contribution percentage of one NHCE in order to pass the Rate Group Analysis for the only HCE in the plan.

Can I do this, or do I need to increase the contribution percentages of all the NHCE's?

The current contribution allocation is

1 HCE: 16.67%
10 NHCE: 5%

Thank you, AJM

You need to follow the terms of the plan, or change the terms of the plan to allow what you want. Note that you can superimpose upon the plan's terms via an amendment under 1.401(a)(4)-11(g) if you want.