The exact procedure may vary over different calls so we advice you to always double check with the official documents. Also, it may be helpful to contact the support team of the RyC program. However, changing affiliation in general tends to be easy. You need a new center that is willing to contract you and this center needs to be on the list of centers that are legally allowed to host RyCs. All Universities and CSIC are. There is a document that needs to be filled. Very shortly you need to argue that the new center is apt to continue your unaltered research proposal. This document needs to be signed by the vice-rectors of research of both universities and by yourself. Next, you need to send this document to the RyC program at the Ministry of Economy and Competitiveness – MINECO (as of June 2015, this should be electronically sent through Carpeta Virtual de Expedientes – Facilit@ found on the MINECO website) who need to approve your proposal. In most cases, they will approve it, given that your unaltered research fits naturally in the new center too. Once given the formal approval by the Ministerio you can sign the contract with the new center. It is *very* important that there is NO day in between your old contract and the new one.