FORTUNE — Future flyers may be getting some help from the Transportation Department when it comes to computing the actual price of air travel, including tacked-on costs such as baggage fees.

The federal government announced a proposal Wednesday that would require a new level of transparency from airlines and ticket agents by asking that they disclose extra costs associated with basic services like a first and second checked bag as well as carry-on items and advanced seating assignments. These additional fees usually aren’t obvious to people sorting through a list of flight options, making it difficult for consumers to grasp the true price of air travel until they’ve already bought their ticket, government regulators said.

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Knowledge is power, and our latest proposal helps ensure consumers have clear and accurate information when choosing among air transportation options,” Transportation Secretary Anthony Foxx said in a statement. Foxx added that his department’s newly proposed rules “will strengthen the consumer protections we have previously enacted and raise the bar for airlines and ticket agents when it comes to treating travelers fairly.”

The agency’s previous consumer-friendly regulations include a 2011 measure to ensure travelers whose bags are lost are reimbursed for baggage fees. The DOT’s previous attempts to force airlines to disclose “hidden fees” at all points of sale have been met with resistance from airlines, which argue that disclosing those additional charges hides the cost of government taxation incurred by the airlines. Industry lobby Airlines for America recently proposed new legislation that would slim down regulations regarding fee disclosure for airlines.

Airlines for America issued a statement Wednesday opposing the government’s latest proposal. “We believe this proposal over reaches and limits how free markets work and will have negative consequences,” the group said. The organization also said the proposal would likely cause airlines to incur added expenses and would “force airlines to pass on the additional costs to customers in the form of higher fares or reduced levels of air service.”

While some airlines don’t charge customers to check their first piece of luggage, other carriers charge anywhere from $15 to $45 for that service. Travels who bring along third checked bag can pay as much as $150.

Meanwhile, Wednesday proposal would also expand the number of airlines that are required to report their on-time performance data and mishandled baggage rates to the agency. Under the proposed rules, smaller airlines such as Spirit Airlines SAVE would be included in that expanded pool. The government is also proposing a broader definition of the term “ticket agent” to include travel search websites like Kayak and Google GOOG , which regulators believe should be subject to consumer protection rules.