"This is not something new. I had informed the prime minister's office earlier that Mar 14 would be my last working day," Saran was quoted by news agency as saying.
There is speculation that the decision comes after the National Security Advisor (NSA) Shiv Shankar Menon's appointment.
Both were Foreign Secretaries and had retired. While Menon retired late last year, Saran had retired three years before that.
While Menon was given the rank of Minister of State following his appointment as NSA, Saran was yet to get it.