The expenses of the shared services referred to in article R. 2512-27 may be shared pursuant to agreements or conventions entered into between the Commune of Paris and the départements of Hauts-de-Seine, Seine-Saint-Denis and Val-de-Marne. The départements may renounce the use of one or more of these services and consequently cease to contribute to their expenditure.
A deliberation to this effect by a departmental council will only take effect from the beginning of the third financial year following its notification to the commune of Paris, unless an agreement setting out the conditions for a more rapid withdrawal is reached between the commune of Paris and the three departments.
During the period provided for in the above paragraph or in the absence of an express agreement or agreements, the costs will continue to be distributed in proportion to the last known value of fiscal potential.