(8)To ensure the timely payment of oversight fees, those fees should be paid within 30 days from the date of issuance of the Lead Overseer’s debit note. To simplify the fee payment flows, and to ensure ESAs have the necessary funds to carry out their planned supervisory activities, annual oversight fees should be paid in a single instalment during the first four months of the calendar year for which such fees are due by critical ICT third-party service providers subject to oversight activities on 1 January of that year or, in the case of critical ICT third-party service providers designated throughout that year, at the latest by the end of that year.