Thanks for getting back to us, @Tracyele.
All earnings are taxable, per IRS regulation.
You may override the tax amounts to zero out taxes, then select customer job. Upon sharing this, I still recommend consulting with your accountant for additional guidance.
You can set up non-taxable per diem payroll item. However, you're unable to track its job when running payroll.
Keep me posted on how this goes. The Intuit Community is always around whenever you need help.
