Hi Connan,
I was able to achieve this functionality in a different way, since Tax code field (Odata) is not retriggered based on the company code selected, we have created another Tax code field and the values are mapped to the new field from search help based on the company code and this field values is mapped to Standard tax code field and the Standard tax code field is made as input disabled... Though it was tricky but here we didnt had much option...
Best Regards
Manoj