Employee - more than one Class

Yes you can, but only to one class.

You may need to set up two contract payments and allocate one to a different expense account and edit the class that way.

But I don'tthink you can actually, when I have tried it.

If an employee has two contracts then you can treat them as being two employees. If you call HMRC they will give you tax codes for each employment. If you give your employees employee numbers (see the "additional info" tab on each employee record) then this person will have two employee numbers. This is a good idea. Quickbooks will also need you to spell the names used for each employment differently in some way. Any difference will do. e.g. If there is a middle name, an initial for one employment and full spelling for the other will work. This will enable you to use two classes as you need. John

 Done:

I've solved my original question:   Go to Preferences/Payroll & Employees/Company Preferences and tick the box 'Job Costing and Class tracking for payroll payment expenses' and then 'Assign one class per Earnings item'