The designers behind premium brand Dolce and Gabbana are reportedly under investigation for failing to declare revenues of about €840m (£734m).
Italian prosecutors have accused designers Domenico Dolce and Stefano Gabbana of setting up a company in low-tax Luxembourg in 2004 and 2005 but operating the business, Gado, from Italy. Sales royalties are taxed at just 3% in Luxembourg compared to a higher rate in Italy.
Italian newspaper reports suggest the unpaid taxes amount to €420m (£367m).
No charges have been brought against Dolce and Gabbana.