Usually, Chelsea submit two squads at the start of September, once the summer transfer window has closed.
This year, we only have to worry about the Premier League, which does have slightly more relaxed rules regarding homegrown players than the Champions League -- though thanks to our deadline day (and day-minus-one), we're in good shape regardless. No Papy Djilobodji sadness this year!
The rules remain the same for this year as last. The 25-man squad cannot contain more than 17 "foreign" (non-homegrown) players, but anyone under 21 (born on or after January 1, 1995) is exempt. If the squad does not have at least 8 homegrown players -- and Chelsea only have 6 (one more than last year!) -- then the registered squad ends up smaller than the 25 maximum.
As per the Premier League website, here's Chelsea's official 2016-17 squad for the first half of the season. The next time any changes can be made to this is during the January transfer window.
Non-HG: Alonso Mendoza, Marcos; Azpilicueta Tanco, Cesar; Batshuayi-Atunga, Michy; Borges da Silva, Willian; Courtois, Thibaut; Da Silva Costa, Diego; Dos Reis Carvalho, Eduardo; Dos Santos Emboaba Junior, Oscar; Hazard, Eden; Ivanovic, Branislav; Kante, Ngolo; Luiz Moreira Marinho, David; Matic, Nemanja; Mikel, John Obi; Rodriguez Ledesma, Pedro Eliezer; Zouma, Kurt Happy
HG: Begovic, Asmir; Cahill, Gary James; Chalobah, Nathaniel Nyakie; Fabregas Soler, Francesc; Moses, Victor; Terry, John George
Or if you're a visual learner (including the four obvious U21s, but all other kids are registered as well, technically):
One interesting sidenote is that Manchester United were able to register Paul Pogba as homegrown, even though up until now, he was thought to have missed the cutoff deadline by a few months before leaving for Juventus. Hmmm...