Airline passengers flying out of the UK now face more expensive flights following a controversial rise in Air Passenger Duty (APD).
Flight taxes rise by up to 55% from Monday as part of the changes, which will generate an estimated £2.3bn for the Treasury.
Long-haul flights will be worst hit and family holidays are likely to be more expensive.
The move has been criticised by airlines, which fear lost business.
Airlines say the increased cost could put off tourists and business people travelling to the UK. Critics also point out that family holidays could become much more expensive.
The travel and aviation industries are already struggling after the recession, as people cut down on foreign holidays.
A group of four people flying economy to Florida will now pay £240 in tax, an increase of 33%. And flying economy to popular holiday destinations in the Caribbean will cost £75 in APD, up from £50 last year and £40 two years ago.
Passengers travelling in premium economy, business and first class will also see hefty increases in the duty.
APD, initially introduced at just £5 for UK and European flights and £10 for longer-haul journeys in 1994, only rose to £10 for economy flights in Europe and £40 for flights further afield by 2007. In the past three years, it has increased dramatically.
Michael O'Leary, chief executive of Ryanair, used the budget airline's results this morning to launch an attack on the tax.
He said: "We continue to switch capacity away from countries like Ireland and the UK where they have a passenger tax -- and remember the passenger tax is a tax at a rate of about 33% on Ryanair's average ticket price, so this government is asking the poorest passengers to pay the most amount of tax.
"But we're growing very rapidly in those countries like Spain and Italy where they scrapped the taxes and have been rewarded with traffic and tourism growth."