Freelancer with EU business clients — when do I actually have to register for VAT in Bulgaria?

Your freelancer friend is right, and this is the single most common compliance gap among freelancers in Bulgaria — two unrelated registrations that everyone conflates. Registration one is the general threshold: mandatory VAT registration when your taxable turnover in Bulgaria exceeds 51,130 euro within the calendar year (the rule since the 2026 changes). Your EU agency work does not even count toward this threshold — B2B services to businesses in other member states are taxed where the customer is, not in Bulgaria. On 40k of foreign B2B work you are nowhere near needing full VAT registration. Registration two is the one that caught you: Article 97a of the VAT Act requires a special, limited VAT registration before you supply your first service to a VAT-registered business in another EU country — no threshold, no minimum, from invoice one. It exists so cross-border B2B services can be reported in the EU-wide VIES system. Under it you do not charge Bulgarian VAT to your German and Danish clients — you invoice at zero with reverse charge noted, and they self-account for VAT at home. You file monthly VAT returns and VIES declarations listing those clients, and note this registration gives no right to deduct input VAT on your own purchases. So yes, if you have been invoicing EU agencies without a 97a registration, you are formally non-compliant. The fix is straightforward: register now and start filing. Penalties for the late registration exist but are modest, and voluntary correction beats being found in a VIES cross-check, where mismatches surface automatically. An accountant can handle the registration and the monthly filings cheaply — see also /guides/bulgaria-freelancer-vs-company-eood for how VAT fits the freelancer setup.