1. ¹ Supervisory authorities shall provide each other with relevant information and mutual assistance in order to implement and apply this Regulation in a consistent manner, and shall put in place measures for effective cooperation with one another. ² Mutual assistance shall cover, in particular, information requests and supervisory measures, such as requests to carry out prior authorisations and consultations, inspections and investigations.
2. ¹ Each supervisory authority shall take all appropriate measures required to reply to a request of another supervisory authority without undue delay and no later than one month after receiving the request. ² Such measures may include, in particular, the transmission of relevant information on the conduct of an investigation.
3. ¹ Requests for assistance shall contain all the necessary information, including the purpose of and reasons for the request. ² Information exchanged shall be used only for the purpose for which it was requested.
4. The requested supervisory authority shall not refuse to comply with the request unless:
   1. it is not competent for the subject-matter of the request or for the measures it is requested to execute; or
   2. compliance with the request would infringe this Regulation or Union or Member State law to which the supervisory authority receiving the request is subject.
5. ¹ The requested supervisory authority shall inform the requesting supervisory authority of the results or, as the case may be, of the progress of the measures taken in order to respond to the request. ² The requested supervisory authority shall provide reasons for any refusal to comply with a request pursuant to paragraph 4.
6. Requested supervisory authorities shall, as a rule, supply the information requested by other supervisory authorities by electronic means, using a standardised format.
7. ¹ Requested supervisory authorities shall not charge a fee for any action taken by them pursuant to a request for mutual assistance. ² Supervisory authorities may agree on rules to indemnify each other for specific expenditure arising from the provision of mutual assistance in exceptional circumstances.
8. ¹ Where a supervisory authority does not provide the information referred to in paragraph 5 of this Article within one month of receiving the request of another supervisory authority, the requesting supervisory authority may adopt a provisional measure on the territory of its Member State in accordance with Article 55(1). ² In that case, the urgent need to act under Article 66(1) shall be presumed to be met and require an urgent binding decision from the Board pursuant to Article 66(2)t.
9. ¹ The Commission may, by means of implementing acts, specify the format and procedures for mutual assistance referred to in this Article and the arrangements for the exchange of information by electronic means between supervisory authorities, and between supervisory authorities and the Board, in particular the standardised format referred to in paragraph 6 of this Article. ² Those implementing acts shall be adopted in accordance with the examination procedure referred to in Article 93(2).

This article of the General Data Protection Regulation is addressed in recitals (123) (133) of the GDPR.*