(5)Competent authorities that use ESCB services are to contribute to the costs of developing and operating the ESCB services according to a defined reimbursement framework based on a cost allocation key. In the light of the significant administrative burden of calculating the reimbursement by competent authorities for past costs in particular, competent authorities that use the SHSDB or the CSDB should only be required to contribute to the costs of developing and operating the respective ESCB service arisen on or after 1 July 2023 for the SHSDB and on or after 1 January 2024 for the CSDB. The existing financial arrangements should therefore be specified further.