"To date, the status of this matter has not changed substantially since the November report, as defendant Gates continues to cooperate with respect to several ongoing investigations, and accordingly the parties do not believe it is appropriate to commence the sentencing process at this time," the document said. "The parties respectfully request that they provide a joint status report within sixty days, no later than March 15, 2019."
Gates pleaded guilty to charges of conspiracy and making false statements in connection with Mueller's investigation into Russia, the 2016 election and alleged collusion between Moscow and the Trump campaign.
Media reported last month, citing unnamed sources, that Mueller might submit his finding by as early as mid-February.
Russia has repeatedly denied interfering in the US election, calling the allegations "absurd," and both Moscow and US President Donald Trump have dismissed accusations of collusion.