In this case, the question "Are bank fees subject to tax?" could have more than one reason, and it's incorrect to assume a single cause without reviewing the details.
Key points
Check the transaction or account details, and then ask the bank to explain the specific reason.
If the reason is related to fees, rejections, or deductions, request a clear statement of the amount or condition that was applied.
The figures, fees and limits in this answer vary by bank and change over time — confirm them with your bank or the official source before acting.