Pre tax dedcution for employee donation

first give some thought as to how this deduction should show up on the W-2.  next determine what this pretax item is actually tax free from, ie fed/state withholding, fed/state/fica/medicare, and also consider if is exempt from unemployment taxes, futa and suta. in your state, also consider any other state or local taxes.

Once you can answer these questions, you know how the item should be set up.  Either custom make your own item, choosing the tax tracking type and check mark the taxability.  Or when you know most of the answers, use the EZ creation of the new item and call it what you want.

Then try a dummy payroll, or use one of the samply companies to run the test.

Donations are not made with pretax dollars. Donations are made with after tax dollars and then the donor gets a deduction from taxable income on schedule A.