According to legal docs obtained by The Blast, the "Walk the Line" star purchased the home late last year and his sister, Summer Phoenix, is a co-owner of the property.
Summer and Affleck's divorce was final in September and the "Manchester By the Sea" star is paying $4,000 a month in child support for the couple's two kids.
Our sources say the brother and sister duo do NOT live together, but Joaquin is simply on the property and loan documents.
The house is marketed as a "tranquil, enclosed space, where the birds love to gather." It was built in 1903 and is a craftsman home, loaded with charm.
It was recently "fully updated, yet maintains many of its craftsman features. Lush outdoor space perfect for entertaining; Large covered porch; Spacious, open-concept kitchen; All new kitchen and baths; Brand new appliances; Full of unique touches."
The million dollar pad is billed as not a "cookie-cutter home."