Hi ,
For the Validity, I have set the Validity of the tax to be valied from the first day of the Month.
What I have did is that the Condition Record set the validity as i said from the first day of the month and i have also create Condition value in VK11 set the validity from the first day of the month.
I agree with Md. Enayet Hossain as the condition record i put it as Mandatory so the error came, but what i need is that this condition must be Mandatory for the Customers Liable for Tax. So when I start to create a new sales Order or orders created from the first day of the month tax will be determined automatically. and for Orders created last Month this condition will be neglected and not determined.