Service charges, inspection fees, and consulting fees are sometimes charged in addition to the premium. States vary considerably as to how they treat such fees. Some states absolutely prohibit such fees. Other states limit how they may be imposed. For example, in Illinois, a service charge must be evidenced by a written document signed by the insured, showing the amount of the charge.
Some states require additional proof that the size of the fee is reasonable.
Several states allow consulting fees, or commissions, but not both. You're probably used to having the carrier handle any premium taxes. However, if you do surplus lines business, or purchasing group business, you may get involved in the collection and remitting of taxes. Bad accounting practices can get you in trouble with tax authorities here. Many insureds need help financing their purchase of insurance.