The deadlines seem to be in line with current year deadlines rather than exactly 3 - years from original due date, IRS says last chance for 2014 is 4/17/2018. (money.stackexchange.com)
Charlie's original due date arrives and Cori and Kacy seek help from a therapist to cope. (sho.com)
This serves another purpose as well: your contractor will have no excuse for not getting work done on time if he / she helped set the original due dates. (smallbusinessesdoitbetter.com)