Abstract:This study aims to test two principles of code-switching (CS) formulated by González Vilbazo (2005): The Principle of the Functional Restriction (PFR) and the Principle of Agreement (PA). The first states that a code-switch between the morphological exponents of functional heads belonging to the same extended projection of a lexical category (N • or V • ) is not possible. The second claims that inside a phrase, agreement requirements have to be satisfied, regardless of the language providing the lexical material. The corpus on which we tested these hypotheses consists of 25,947 authentic text messages collected in Switzerland in 2009 and 2010. In our corpus, the PA is maintained. The PFR also seems to hold, even if data is limited. Interestingly, contradicting examples can be explained by phonological principles or the sociolinguistic background of the authors, who are not native speakers. Overall, the evidence found in spontaneously written non-standard data like text messages seems to confirm the validity of the two principles.