Log into www.principal.com to review your account and make any change to your 401(k) plan (Home Page>Contributions>Manage Contributions). You have the option of contributing to both Pre-tax (Traditional) and After-tax (Roth) accounts.
Be sure to submit well enough in advance for processing (changes requested will be effective the following pay period) or as administratively feasible.
Note: all employees, upon hire, are automatically enrolled to defer 6% of their salary; beneficiaries are set up according to state regulations. You must login to make changes to your deferral, beneficiaries or investment strategy. Employees are also automatically enrolled to increase their contribution percentage each January unless you log in to opt out. You may also elect to increase your percentage by more than 1%.