Koy,
The rates I suggested include all applicable taxes, surcharges, bonus’s and anything else you can think of. I will not be surprised by extras. If you insist on adding 25% VAT then the rates are as bellow.
1) Salary 16,000 Baht / month for Mon – Fri 6 am – 6 pm
2) Overtime 50 baht / hour after 12 hours
3) Saturday, Sunday, Holiiday 50 baht / hour