FM or Bapi for Customer Change

Hi Gurus,

I need Bapi or FM to change the customer only with new Tax classification.

Here i am getting the new Tax values thru selection screen for a customer. when i pass these values thru internal table i need to change the customer tax corresponing to given customer in selection screen. for this i need BAPI or FM.

points will be rewarded for helpful answers.

Regards,

Balu