Clarence Thomas received rental income from a firm called Ginger Limited Partnership, WaPo reported.
The real estate firm's partners included Thomas' wife Ginni Thomas, her parents, and her 3 siblings.
But since then, Thomas reported receiving a total of $270,000 to $750,000 from the defunct firm, records reviewed by WaPo showed.
A Supreme Court spokesperson did not respond to a request for comment.
Federal law stipulates that government employees, including Supreme Court justices, must disclose real estate transactions worth more than $1,000.