It was believed the capital Bangkok was targeting its inaugural grand prix in 2014.
But F1 chief executive Bernie Ecclestone has been quoted in the Wall Street Journal as saying the first Thai street race, staged under floodlights, will be in 2015.
"An F1 race is likely to take place here in early 2015 instead of in 2014 in our initial plan," Kanokphand Chulakasem, governor of the Sports Authority of Thailand, told the Bangkok Post.
It is believed Red Bull, whose co-owner Chalerm Yoovidkya is from Thailand, is involved in the preparations.
"I can say that it is almost 100 per cent certain that Thailand will host an F1 race," said the energy drink's representative Michael De Santiesteban, who reportedly met with Ecclestone last month.
"With Thailand on the calendar," he added, "a current race is likely to be removed."