Each bank has its own rules, be specific of the bank
I bank with Kasikorn and can speak for them, here are the rules -
Account maintenance - Savings:
Baht 50 per month for an account inactive for more than one year, with outstanding balance of less than Baht 2,000
https://www.kasikornbank.com/en/rate/fee/ChargesDoc/Servicingfeesfordeposits-andotherservicecharges-en.pdf