Where, pursuant to the provisions of the second paragraph of Article 30 of law no. 83-663 of 22 July 1983 supplementing law no. 83-8 of 7 January 1983 relating to the division of powers between municipalities, departments, regions and the State, the department or authority responsible for the organisation of urban transport is required to repay to the legal entities referred to in the first paragraph of the same article a fraction of the right to compensation that they receive, these repayments must be made within a maximum period of one month following the payment of each instalment of the general decentralisation grant or, failing that, of each advance, in respect of the taxation transferred, unless the parties agree on different arrangements.