Where did you read that?
The foundation received its official non-profit designation from the Internal Revenue Service in December,
according to the Associated Press, and will be required to file public tax documents in the future. No public financial filings have yet been made.
So they received their non profit designation in December 2020, so you only file annually in arrears.
https://eu.usatoday.com/story/news/...claim-blm-co-founders-real-estate/7241450002/
So these claims about buying properties are not backed up by evidence. The claims were made by the NY Post - the US equivalent of the Sun.
For this claim, like any others we fact-check, the burden of proof is on the speaker. The post provided no proof of such a connection, the author did not respond to provide any, and we found none in our research, though documents are limited given the nature of the organization and Khan-Cullors' employment history.