A member submitted a receipt for the cost of using a Vrbo property for a YW overnight activity. The receipt shows property fees, Utah sales tax, and the total for all of the above, which constituted the total amount due. Below that total, the receipt shows more than half of the amount due was paid using Vrbo rewards points which the member had previously accumulated. Essentially, the member donated the monetary value of their Vrbo rewards points to pay a large portion of the amount due, then they paid the remaining balance out of pocket. The member was only reimbursed for the out-of-pocket portion they paid.

How much of the original Utah sales tax should the church claim for this reimbursement?
My gut feeling is that the church can only claim sales tax on the portion that the member paid out of pocket (after the value of the Vrbo rewards points was subtracted from the amount due). However, the bishop feels the church can claim the entire original sales tax listed before the Vrbo rewards points were applied.
Who is right? Me or the bishop?