The IOM said the six million who were displaced represented around 15 percent of Iraq’s total population.
“For the first time in nearly four years, the number of displaced Iraqis has fallen to below two million,” the agency said. “Nearly four million have returned home.”
According to the IOM, the displaced who have returned home cited several reasons for their decision, including “the improved security situation (and) availability of housing”.
Others said they were encouraged to return by community leaders, friends and relatives, or simply had the financial means to do so.
But those who are still displaced — 1,931,868 people — complain of lack of means and job opportunities, as well as insecurity and of damaged homes and infrastructure, said the IOM.
Prime Minister Haider al-Abadi declared “victory” in December in the fight against ISIS.
But sleeper cells still operate in the country from sparsely populated areas, including desert regions near the border with Syria.