Add Tax Number in BP Master data

Dear All,

I have a requirement to add tax number(for example RFC Number) in the master data of all the BPs in Mexico.

As per my understanding if in configuration we create a Tax number category for Mexico (SAP has already provided a standard Tax category for Mexico as MX1) a field will become available in BP master in identification Tab where we can maintain the Tax number.

My problem is that I have already created Tax Category MX1 in config through T.Code BUPA_TAXNUMTYPE but I see no new field in BP master to enter the Tax number.

Can you pls suggest if I am missing something.

Thank You

Regards

Sachin