2106 no longer exists. This: "and not employee expenses via 2106" means separating the S Corp mileage and turning that in for reimbursement. There is no deduction for it, because you get Reimbursed for it, and under an Accountable Plan, that reimbursement is not taxable. So, as one previous All Star posted to this community: you cannot write off what you did not write on. No Income involved, when it's Reimbursement per the Accountant Plan rules.

Yes, other mileages for other activities are Personal from the perspective of the S corp. Now that person handles the rest of their mileage per the other rules that apply to those other amounts.

"a portion of the mileage does relate to managing a rental property out of state, so schedule E treatment would work. Also, a portion may relate to preparing a home for a "flip" sale."

It seems your client has at least 2 other operations, separate from their S Corp activities, then. And commuting doesn't go anywhere in taxes for mileage allowances.