I can’t add tax in purchase order list
You need to provide more information about your problem, @Kunal_Rabhadiya. What do you mean by “purchase order list?” If you are referring to the register of purchase orders that appears when you click on Purchase Orders tab, that is not the place to add tax. If you are referring to adding tax to a line item in a purchase order, that is done on the entry screen after clicking New Purchase Order at the far right of the line. You might have to scroll over to that position, depending on your screen size. Can you post a screen shot of where you are having trouble?
When I create new purchase invoice . I CNt add the tax percentage . I CNT even see the column of it.
It is not a column; it is a rectangular field with a dropdown menu. You must have entered tax codes under Settings to see anything. You may have to scroll to the right to see the field.