Income tax:

In Thailand everyone who has an income and is living in Thailand must have their own tax ID number. Those who earn less than 150,000 Thai Baht are exempt from income tax. An individual is able to file their own tax return but all returns need to be in Thai, so non-Thai speaker people will have to seek the help of an accountant. The Thai tax year runs from 1st January to the 31st December and the tax return should be with the tax office by the 31st March, to cover the previous tax year

For group statements, consolidated tax returns are not allowed for corporate income tax purposes and each company has to file its own tax return.

VAT:

The Thai value added tax rate is at 7% for sale of goods or the provision of services.

Sources:

http://www.expatfocus.com/expatriate-thailand-taxation

http://www.mazars.co.th/Home/Doing-Business-in-Thailand/Tax/Value-Added-Tax-VAT-in-Thailand

https://www2.deloitte.com/content/dam/Deloitte/global/Documents/Tax/dttl-tax-thailandhighlights-2017.pdf