The Neroverdi signed Boga in 2018 for just €3.5m (£3m), but the Blues inserted a buy-back clause.
The French winger, 23, has finally settled in Serie A this season, hitting six goals and contributing three assists.
His form has not gone unnoticed around Italy either, with Napoli strongly linked, though a return to Stamford Bridge now appears to be a distinct possibility due to the buy-back clause initially inserted into the deal to send him to the Mapei Stadium.
“Chelsea can redeem him in June,” Carnevali told Goal.
“We have a great relationship with the club and we already met them before Christmas – also for other business.
“We like to have what we have with Barcelona, to have a collaborative relationship.
“They can take him back but we can also re-sign him, everything is open.”
Sassuolo are now 13th and 10 points clear of relegation.
Boga will feature next against bottom club SPAL on Sunday.
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