how can i allocate payroll expenses for a person who works accross classes

Hi, Willie. You can split the employee’s hours or pay and assign each portion to a different class when running payroll.        

Here's how:        

1. Go to the All apps menu > Payroll dropdown> Employees.  
2. Run payroll, then click the vertical ellipsis (⋮)under Actions.  
3. Click Edit class & projects and +Add split, enter the intended amount/hours worked, and choose the associated Class for it.
4. Once done, click Confirm, then proceed to Preview payroll > Submit payroll. 

This method should help split your labor costs appropriately.

Feel free to add a reply below if you have other concerns.