The person spoke on condition of anonymity Saturday because agreement is subject to a physical.
Chacin had asked for $2.6 million in arbitration and had been offered $1.7 million by the Rockies. The 25-year-old right-hander was eligible for arbitration for the first time after going 3-5 with a 4.43 ERA in 14 starts last year, when he missed more than three months because of right shoulder inflammation. He made $482,000.
His agreement was first reported by The Denver Post.