( CNN ) -- The U.S. Department of Transportation slapped United Airlines with a $ 30,000 fine Friday for violating price advertising rules , and the airline also will have to pay the balance for a previous infraction . Under DOT rules , airlines must disclose the full price of air travel to consumers . `` Our fare advertising rules are designed to ensure that consumers know how much they will pay for a ticket and are able to compare prices when choosing which carrier to fly , '' Transportation Secretary Ray LaHood said in a statement . The department found that United failed to disclose a 7.5 percent federal excise tax for 60 hours on the initial results page of its Web site . United said it is committed to advertising its fares clearly . `` In this unique case , due to a programming error , the initial fare display inadvertently placed the 7.5 percent federal excise tax in the 'taxes and fees ' section , rather than in the base fare , '' said spokeswoman Sarah Massier in an e-mail . `` Immediately upon learning of the programming error United took action to move the tax to the base fare . '' Government taxes and fees per passenger are the only charges that are not required to be included in the published fare , according to the DOT . The new penalty means United also will have to pay the balance on a fine for a violation over the summer . In August , the DOT fined United $ 75,000 for not disclosing taxes and fees in the initial advertised fares on its Web site and for showing one-way fares that were only applicable for round-trip travel . The airline was required to pay $ 37,500 of that penalty , with the understanding that half would be forgiven if it had no further violations within the next 12 months . United now is required to pay the other half of the $ 75,000 fine .
Under DOT rules , airlines must disclose the full price of air travel to consumers . United violated price advertising rules twice in five months . Government taxes and fees per passenger are the only exception to the rules .