You will need an apostille certificate, also known as the Hague Apostille, if your country has asked you to legalize documents issued in the United States as proof of authenticity. Once done, these documents can be used abroad. There is a mutual agreement between the countries that have signed Convention 12 of the Hague Convention, according to which the Member States will accept documents apostilled in one of the other Member States. Since Bulgaria is a member of this agreement, once you have confirmed your apostille Bulgaria requirements with the acquiring foreign authority, it is wise to hire reputable service providers such as USApostille to do the work for you. This saves time and money. If you use someone who is familiar with all the procedures involved, you can complete your apostille on time and with ease. The Apostille stamp is placed on the back of a document that is permanently attached to the delivered document. It will then be recognized as authentic in Bulgaria. As it is glued and sealed with the Apostille seal of the U.S. Department of State.