The country has before said it aimed to seek membership of the Comprehensive and Progressive Agreement for Trans-Pacific Partnership (CPTPP), as competition intensifies in electronics and agriculture from rivals such as Vietnam and Malaysia.
Membership is opposed by opposition parties and some business groups.
But Auramon Supthaweethum, director general of the Department of Trade Negotiations, said on Monday that it would boost Thailand's gross domestic product (GDP) by 0.12% or 13.3 billion baht (US$409.61 million), with investment up 5.14%, and exports up 3.47%.
Without that, the economy will lose 26.6 billion baht or 0.25% of GDP, with investment down 0.49% and exports down 0.19%, she said in a statement, citing the ministry's study on CPTPP membership.
"After the coronavirus pandemic, trade and investment rules will change... It's necessary for Thailand to seek new partners or trade pacts, such as CPTPP, to make it competitive for trade and attractive for investment," Auramon said.
The study will be presented to the cabinet to decide whether Thailand will join the pact, Auramon said. The cabinet meets every Tuesday, but it is not clear whether this week's session will debate the matter.
If Thailand decides to join, it will set up a committee to negotiate rules and conditions. The decision would then need approval from parliament, Auramon said.
Those opposed to membership include Move Forward opposition partly leader Pita Limjaroenrat, who has said it would have a negative impact on the economy.
Member countries including Japan and Canada signed the CPTPP deal in 2018, without the United States.
The original 12-member agreement, known as the Trans-Pacific Partnership (TPP), was thrown into limbo in early 2017, when President Donald Trump withdrew from it.
(US$1 = 32.47 baht)