THE EUROPEAN COMMITTEE OF THE REGIONS  stresses that despite its complexity, early action to prevent fragmentation in the first place would still be far less difficult than ex-post harmonisation of 28 national frameworks and countless local and regional regulations;  finds that the Commission's communication provides elements and criteria for assessment without giving a full response, which will inevitably result in differences in interpretation and further fragmentation of the single market; therefore calls on the Commission to come up with a clear legal framework that ensures that fair competition principles are upheld; regrets, here, that the Commission's approach seems to be to let the European legislator only endorse a certain number of judicial decisions;  questions whether the Services Directive's definition of "service provider" is still appropriate, since its current wording captures any economic activity, including the many highly infrequent and non-professional activities provided by peers;  underlines in particular the case of tourist taxes, which are a key concern for many local and regional authorities, since in many locations where such a tax applies, it is not collected on stays reserved through collaborative economy platforms; adds that this breach of regulation cannot be tolerated, that it creates unfair competition vis-à-vis traditional accommodation providers, and furthermore deprives local and regional authorities of revenue;  supports the establishment of a "forum of collaborative economy cities" to share experience and exchange good practice, which besides the CoR should involve the European organisations and networks active in the local and regional dimension of the collaborative economy and liaise with the relevant thematic partnerships of the Urban Agenda for the EU.