More here: https://www.capital.bg/politika_i_ikonomika/bulgaria/2019/07/15/3938624_ot_nap_sa_iztekli_lichni_danni_na_milioni_bulgarski/
(use google translate)
Is the SSN secret in Bulgaria? Here in Argentina the DNI is public and put in a lot of documents, list for voting and other stuff, so nobody expect it to be a secret.
