The Bank of Thailand (BOT) also allowed listed SMEs to participate in the programme, which started in April as part of a larger 1.9 trillion baht coronavirus response package.
The BOT has approved about 119 billion baht of loans so far and has twice said it planned to extend the programme by six months.
Southeast Asia's second-largest economy suffered its deepest contraction in 22 years in the second quarter as the pandemic battered tourism and domestic activity.
The BOT predicts a record economic contraction of 7.8% this year.
(Reporting by Orathai Sriring; Editing by David Holmes)