Passengers pay the cost on the meter, plus a 50-baht airport charge and any tolls along the way, which usually amounts to another 50 to 70 baht. Alternatively, taxis can be flagged outside departures or on the main road. When taxi drivers suggest a flat rate, gently but firmly say you prefer to use the meter. If you agree to the flat rate, be aware that a 200-baht fixed price is reasonable. Anything above 300 baht is exhorbitant.
Tolls are extra, of course.
Be ready with small bills as some cabbies often annoyingly claim to be short of change. Using the meter, you should never have to pay more than 300 baht, regardless of traffic or distance. If you happen to be serviced by an unscrupulous cabbie, make use of the complaint form handed to you at the airport control counter. The form lists the numbers to call. Top Limousine Limousine services, jointly run by Thai Airways and Airport Associate, cost between 500 baht and 650 baht per trip into town.