how could you create such material master?
I just tested it and it is not possible to save a material master without giving a tax classification.
SAP issues message M3 015 as a S message.
All programs that issue this message, issue it as error:
LMG80U11
LMGD1I5G
MM03MI02_STEUERN_ERZWINGEN
How had you been able to create a material master with an initial entry for the tax classification?
I can only get such initial entries, when I assign a new plant with a country that is not yet among the old tax classification to the sales org/distribution channel combination.
And then I cannot save without maintaining a value in that field. But without being able to save no MLAN record is created.