If you want the default WCC Group or Worker's Compensation Code from the employee's Employee Payroll Page > Class/Schd tab, use the table upempl for US payroll or cpempl for Canadian payroll.  The fields are wcc and wccgroup.  For the description you can use a case statement or link to another table for the setup of the code.  I'm not sure what the table for setup is off the top of my head.

If you want WCC Group or WC code that was processed from payroll, there are different tables you can use depending on the stage of the payroll.  For example, if you want history of WC information from payrolls that have been posted, use table upchkd (US Payroll) or cpchkd (Canadian Payroll).  There are multiple fields that start with wc.  You can right click on the field and browse data before inserting it on your report to make sure it is the field that you want.

In the  table UPEMPL, the fields WCGROUP and WCC show the WC Group and WC codes assigned to employee.  To get descriptions and rates for these codes you will need to link to the UPWCCD table which holds WC setup data.

Also, the WC data is stored on the Employee Earning record level as well in the UPEMPD.WCCGROUP and UPEMPD.WCC fields.