In the context of a bank reconciliation, a bank service charge is typically considered a d deduction from the book balance. This is because service charges are fees that the bank deducts directly from your account, reducing the amount that you have in your accounting records.
When you perform a bank reconciliation, you compare the bank’s records to your own. While the bank balance may reflect the deductions accurately, your book balance will need to be adjusted to account for any service charges that haven’t yet been recorded in your personal accounting. Hence, you deduct the service charge from your book balance to align it with the bank’s records.