Across Europe, we can see the trend toward the incorporation of e-invoicing obligations. A large number of countries have already adopted the main regulations, and some of them have already started with e-invoicing. Mostly, it represents a special format for sending invoices and a special platform on which they are sent and processed. But every country has its own rules, phases, subjects, deadlines, technical requirements, etc. The e-invoicing system in Bulgaria is in the implementation phase but is only at the beginning.
Source: fiscal-requirements.com