For all grant agreements signed as of 1 January 2017 onwards, legal entities established in Switzerland will be treated as entities from an Associated Country.
Please consult the guidance on the Participant Portal:
http://ec.europa.eu/research/participants/data/ref/h2020/grants_manual/h...
http://ec.europa.eu/research/participants/data/ref/h2020/other/hi/h2020-hi-swiss-part_en.pdf