Bayliss took the job in 2015, leading England to a home series win over Australia and to the 2016 World Twenty20 final, but he informed England cricket director Andrew Strauss a year ago that he was planning to step down.
"I told Andrew Strauss probably 12 months ago that September 2019 is when I'm contracted to and that would see me out," Bayliss said after England's 4-0 Ashes defeat in Australia.
"I've never been anywhere any more than four or five years. Whether you're going well or not I've always felt that round about that four-year mark is time to change.
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"A new voice, a slightly different approach slightly reinvigorates things, so I passed that on to him 12 months ago."
Bayliss, 55, also led England to a test series win in South Africa and he will leave the job next year after a home summer that also includes the World Cup in England.
"I've got no problem working towards a long-term goal even if I'm not going to be there," said Bayliss, a former Sri Lanka coach.
"You leave a coaching position hopefully with the team in a better place than when you started. Joe Root as the captain will still be there and there's a base of six or seven players that will still be young and good enough to be in the team," he added.
"The captain is in charge, but we're there to help out. Joe is a young captain and I would expect in four years when he comes back, with another four years' experience and an away Ashes under his belt, he'll feel a lot more comfortable."
(Reporting by Shrivathsa Sridhar, editing by Ed Osmond)
