Why is OPTE using the Previous Aggregation method instead of Flat Tax for Supplemental payroll

Summary:

Supplemental payroll used Calculation Method Previous Aggregation for an employee instead of the expected the method to be Flat.

The supplemental payroll period 8 2026 Biweekly, period end 4/11/2028; they had prior regular wages taxed in the year (last pay period 7 2026 Biweekly, period end 3/28/2026).

We are trying to determine why this employee was not calculated using the Flat Rate calculation method.

Content (please ensure you mask any confidential information):

Supplemental Payroll -

Regular Payroll -

Version (include the version you are using, if applicable):

26A

Code Snippet (add any code snippets that support your topic, if applicable):