About this one. If you ask your client for CNPJ number（Cadastro Nacional da Pessoa Juridica） or CPF(o cadastro de pessoa Física) so that you can send your samples to them. They will understand. As this is a regulation of Brazil customs. Any parcel that send to this country, their customs needs one of these numbers...don't know the reason though..hope this helps. :)

Both super answers, but TNT is not great at sensitive stuff. Use Fedex. They often make it.

I think I see the difference. The TNT account number is the number that TNT uses internally to identify a customer. The Customs Duty office is separate from TNT and would not recognize TNT's internal account number for that customer. Because of this, a separate number - the TNT duty number - is used to identify the customer to the Customs Duty office, which will recognize this number and use it to process any payment of duties. Was I close?