So it gets complicated cause the correct and official way for them to defer you is remove you from the list and then you need to contact DCAS and FDNY CID to get put back on and they have a lot of inter agency paper work and communication to put you back on which gets confusing and can take weeks or months and you may not get back on in time for the next academy , the other and easier way to go about it is when they call you with the offer you need a legitimate reason why you can't do this academy but would be able to do the next one and they can just put a note in their system to call u for the next one and it's not an official declination, depends on the investigator that calls you with the offer and your reason