(66)Fees or charges should cover, but not exceed, the costs, including overhead costs, incurred by the competent authorities to perform official controls. Overhead costs could include the costs of the support and organisation necessary for planning and carrying out the official controls. Such costs should be calculated on the basis of each individual official control or on the basis of all official controls performed over a given period of time. Where fees or charges are applied on the basis of the actual cost of individual official controls, operators with a good record of compliance should bear lower overall charges than non-compliant ones, as they should be subject to less frequent official controls. In order to promote compliance with Union legislation by all operators irrespective of the method (based on actual costs or on a flat rate) that each Member States has chosen for the calculation of the fees or charges, when fees or charges are calculated on the basis of overall costs incurred by the competent authorities over a given period of time, and imposed on all operators irrespective of whether they are subject to an official control during the reference period, those fees or charges should be calculated so as to reward operators with a consistent good record of compliance with Union agri-food chain legislation.