The Bank of Thailand has declared Jan 2, 2015 a holiday for Thai banks in line with a cabinet resolution earlier.
For the New Year holiday, banks will therefore close for five days from Wednesday, Dec 31 to Sunday, Jan 4.
Normally, banks are not allowed to close for more than four consecutive days for fear the financial system will be disrupted.
The Bank of Thailand said it wanted to support the measure to promote tourism, which would help the overall economy.
Making the announcement long in advance should give businesses enough time to prepare and eliminate the impact on the financial system, it said.
In any case, financial institutions can opt to open certain branches such as those at shopping malls as they see fit provided they comply with labour laws.
The cabinet earlier declared Friday, Jan 2 an extra holiday to promote local tourism and allow people to enjoy New Year festivities.