Collecting Customer Tax ID Number

I am setting up my first instal of zen cart, 1.3.8. This store is wholesale and will only sell to resalers so I do not need to collect tax but do need to collect customers tax id numbers. I am searching for way to do this - any suggestions would be greatly appreciated. Users must register to access site so would be easy to collect at that registration point if possible.

Thanks!

You'll need to do 4 things:

1. Add a field to the customers table in in the database to store the tax id;
2. Modify an override copy of includes/templates/template_default/templates/tpl_modules_create_account.php to collect the information;
3. Modify an override copy of include/modules/create_account.php to take the info from the submitted form and put it in the database; and
4. Modify your admin customers page to view the info.

Thanks for the suggestion!