Como have tabled a package worth around £25.5m – a fixed fee of €25m (£21.4m) plus €5m (£4.3m) in bonuses considered straightforward to reach – for the 27-year-old centre-back, with talks between the two clubs described as gaining real momentum.
Chalobah, an academy graduate who made 34 league appearances last season, scoring three times, is understood to be keen on the move to Italy, where he would offer Premier League experience and the versatility to play in either a back three or a traditional central-defensive pairing.
Chelsea's growing confidence in Maxence Lacroix, who they are closing in on signing from Crystal Palace, has made the club more willing to sanction Chalobah's exit and free up space in a crowded defensive department, while also generating significant profit in their accounts as an academy sale.
Chelsea have also been in talks over a deal for Rayo Vallecano full-back Pep Chavarria throughout the summer, though the Spanish club are standing firm over their asking price. Chavarria has a £42.4m release clause, though Rayo would reportedly be willing to sell for around £30m.
Chelsea, however, are prepared to offer only up to £21m, some way short of Rayo's valuation, despite personal terms being effectively agreed with the player.
The Blues are seeking additional cover at left-back following the £47.5m sale of Marc Cucurella to Real Madrid, with Dutch defender Jorrel Hato expected to be given the chance to establish himself as first choice, though support is still considered necessary.
The former Real Zaragoza full-back would add experience new head coach Xabi Alonso has identified as a summer priority. Chelsea, who have had a £15m bid for Chavarria rejected, also saw an £8m offer for Sunderland's Granit Xhaka turned down; the Switzerland midfielder played under Alonso at Bayer Leverkusen and had been targeted to add leadership to the squad.