Healthcare in Bulgaria is provided by the National Health Insurance Fund. It is compulsory for all residents to contribute to this fund and it is essential for obtaining a National Health Insurance Card. The cost of healthcare of individuals is normally split between the state, the employer and the individual.
European nationals are therefore qualified to receive free healthcare from state owned institutions in Bulgaria. For this, an EHIC (European Health Insurance Card) is required. This card is used by the hospital, in the case of claiming payment for treating you. Sometimes ,you may have to pay yourself and reclaim the money afterwards.
See link below for more information and to apply! (UK residents)