According to the Revenue Department's directive (clause 1 Paw 50/2537). Estimated taxes must not be less / more than 25 percent without and valid reason, and I has consult with Wannaporn that this year HTH's income around 700,000,000 THB and I think that 10% both of 2 methods are can be cover for the 25% risk (If no unexpected event occur, like the year we got a flood)