The Pre-Tax Group field on the PR Deductions/Liabilities form, Info tab.
For deduction codes, when the Calculation Category drop-down is set to E-Employee and the Pre-Tax Deduction check box is selected.
For liability codes, when the Limit type is Rate of Earnings and the 401k Liability check box is selected.
Enter the pre-tax deduction group for this deduction or liability code, or press F4 to select from a list of valid pre-tax deduction groups.
You should enter a group here when you have multiple 401(k) deductions or 401k employer match liabilities that require a combined limit.