I have some orders is placed, when tax rule is not build. After some times, I will create tax rule. Now all orders is placed with tax rules. But I want to add tax rule in old orders. How can I do this in Magento-2.1 ? Please guide me.
Logically, it should not be implemented as Magento does not recalculate total and other price-related with an order.
As an e-commerce view, it is not good logic to tax after orders. Tax changes after order place make a user confuse and it becomes create trust issue over the website.
In my point of view, if you want to change the tax amount why you do not cancel old order and create the new orders from admin for those orders.