The Blues reportedly opened talks with Die Werkself after agreeing to terms with Havertz on a five-year contract.
There's still some distance between the two sides. Leverkusen want €80 million before add-ons, Romano reports, while Chelsea are only willing to pay that much after the fact.
The Bundesliga outfit reportedly valued Havertz at €100 million earlier in the summer.
Chelsea are in a position to spend after clinching a Champions League berth on Sunday. They've already dropped a reported €40 million on Moroccan star Hakim Ziyech, and another €53 million on German striker Timo Werner. Manager Frank Lampard denied rumors that the club would need to sell midfielder N'Golo Kante to fund a move for Havertz.
The attacking midfielder ended the season as one of Germany's hottest properties, becoming the first player in Bundesliga history to score 35 league goals before the age of 21. Havertz also captained Leverkusen in the final months of the campaign.