Italian tax authorities believe that Fiat has underestimated the value of its U.S. Chrysler arm to the tune of €5.1bn, which could lead to an additional tax bill of €1,2bn, Bloomberg reported on Thursday.

Tax authorities issued a preliminary report in October, assessing the 2014 FIAT-Chrysler merger. A final report will be submitted in December 2019.

The tax probe comes while Fiat Chrysler is finalizing merger talks with PSA, the maker of Peugeot and Citroen, over a planned $50bn merger to create the world’s fourth-largest automaker.