I don't quite understand how you can track item expenses through payroll, but it doesn't allow you to allocate how much of that expense goes to which Customer: Job
Is there a way to bypass this so that you can do that?
As a service based industry, we have guys working on multiple jobs per week. Not all of those jobs get item expenses tracked to them, but doing what QuickBooks suggests (below) on how to handle this, divides the item expense between all jobs on that week's payroll. Dumb!
Track expenses by job
When you create or edit payroll items that are additions, deductions or company contributions, QuickBooks Desktop displays a checkbox. The checkbox called Track Expenses by Job in the Name is in the Paychecks and Payroll Reports window of the Payroll Item Setup wizard. If you select this box, Quickbooks Desktop prorates the items on employee paychecks the same way it does company-paid taxes. See the steps below for additional instructions.
Marking Track Expenses By Job won't add a Customer: Job column to the payroll items listed under Other Payroll Items on a paycheck. Instead, in reports, these items are divided based on the division of the earnings items on the paycheck.
Turning on Track Expenses by Job doesn't affect existing transactions.
The article you quoted only refers to "Payroll items that are additions, deductions or company contributions" - it does no apply to hourly wages or salary, or to goods & services purchased.
I'm not clear on what you want to track to jobs and how, but since your talking about payroll I assume it must be wages.
If you want to allocate employee time you have to use time tracking, or manually enter hours per job into the paystubs. Regardless of which method is used not all hours have to be allocated to jobs. You can still have some unallocated hours per employee.
Splitting 'other payroll items' per job means that things like employer health premiums and payroll tax costs will also be allocated - not just the base wages.