SBT taxable period is a calendar month. SBT return (Form ภธ. 40) must be filed on a monthly basis regardless whether or not the business has income. SBT return and payment must be submitted to the District Revenue Office within 15 days of the following month. If taxpayer has more than one place of business, each place of business must file its return and make the payment separately unless there is an approval from the Director-General.