But more than six months of protests leading up to the May 22 coup - and the military takeover itself - have reduced the number of arrivals this year.
Ten percent fewer foreigners travelled to Thailand in May compared to the same month in 2013, according to Ministry of Tourism figures.
The visa crackdown expects to depress these figures further: Foreigners living in Thailand illegally on short-term visas have typically marked themselves as tourists on arrival cards, causing artificial inflation of the numbers on tourism data.
How immigration rules will be enforced still isn't clear.
Airlines contacted by Al Jazeera, including the national carrier Thai Airways and budget operators Nok Air and AirAsia, said the government has so far not asked them to vet passengers before they board, raising the possibility some could be turned away after landing.
"The immigration Bureau will be taking the lead on this initiative," said Piyasuda Archasantisuk, a Bangkok-based spokesman for AirAsia. "Our normal procedure is to conduct a basic document check prior to the passenger's departure."
With stricter enforcement not due until later in August, the number of people leaving the country remains low but could increase, said Thaivisa.com's Anderssen. Some have headed to neighbouring Cambodia but most want to stay, he added.
"Many of these people have been in Thailand for years," he said. "For them, there simply is nowhere else.