Hi,
could you please explain how you fix the fixed value of tax...i mean is it fixed based on quantity? or randomly you are determining the tax value trough some other calculation. please explain the details.
if you want to insert manual tax condition at po item conditio, ie MM pricing, you may crate a manual condition a you hav to create a new condition type in m/06 with condition categary D. Now you have to write a routine with the help of abapers so that this new condition value will be copied against some appropriate tax condition type andthe same will be displayed in taxes tab of po.
if you can determine how the fixed amount is calculated, i mean if its like cement material excise can be fixed rate per pack. if this is the case, you can incorporate the same within the tax procedure itself and you may maintain condition records accordingly. only thing is for this condition type, calculation type will not be %. You may create new tax condition types with reference to jmoq condition type in obq1.
hope its helpful. If you can give further more details as requested above we can help u more.
Regards,
AKPT