This idea has been merged into another idea. To comment or vote on this idea, please visit BO-I-103 Need to restrict item's tax name modification.
Currently, tax group can be defined at article level as well as supplier level. On creation of items, it is not clear that from where the tax should flow, this is leading to confusion among clients. In all modules, the flow should be similar. This needs to be studied and revamped.
Also, tax group provision is given in customer master's procurement tab but not in supplier master.