On 16 June 2021, Switzerland and the United Kingdom signed a mutual agreement to establish the mode of application of the arbitration process provided for in Article 24(5) of the Switzerland - United Kingdom Income Tax Agreement (1977) (as amended through 2017). The competent authorities further agreed that they may modify or supplement the mutual agreement by an exchange of letters between them.
The mutual agreement applies to any request for arbitration made pursuant to paragraph Article 24(5) of the treaty after that provision has become effective. In respect of cases presented to the competent authorities before the date of signature of the mutual agreement, the time limit for the competent authorities to request further information from the taxpayer under the provisions of subparagraph b) of paragraph 3 of the mutual agreement will be 90 days from the date of signature of the mutual agreement.