A Senate Subcommittee report found airlines have brought in more than $12 billion in fees from things that used to come with the price of a ticket.

In a 55-page report, the majority staff of the Senate Permanent Subcommittee on Investigations released on Tuesday its findings after a year-long inquiry into five U.S. airlines’ ancillary fees, which the report said have led to higher costs and worse experiences for consumers and, in some cases, tax avoidance by the airlines.