How do I actually register as a freelancer in Bulgaria — BULSTAT, NRA, quarterly taxes?

Wanting to understand the machine first is the right instinct — and yours is simple enough that you may indeed not need monthly help. The sequence: first, with your residence certificate, register in the BULSTAT register at the Registry Agency as a freelancer (svobodna profesiya) — a modest fee, done within 7 days of starting activity, and you receive your BULSTAT number, which for EU citizens doubles as your tax identifier. Second, file the declaration for commencing self-insurance (form OKd-5) with the National Revenue Agency, choosing whether to insure for sickness benefits too (slightly higher rate). That is the whole registration — no notary, no capital, no company. The ongoing rhythm: monthly, pay social and health contributions by the 25th of the following month, on an insurable base you choose between the minimum (620.20 euro, the minimum wage) and the 2,300 euro cap, settled up annually against real income. Quarterly, pay advance income tax — 10 percent on income after the 25 percent notional expense deduction and after contributions — by the end of the month following each of the first three quarters; no advance for Q4. Annually, file the tax return by 30 April with the annual contribution equalization, and pay any balance. One trap for your situation: translating for VAT-registered business clients in other EU countries triggers a limited VAT registration under Article 97a before your first such invoice, regardless of income — reverse-charge invoicing plus monthly VIES declarations. That, plus the first annual return, is where a few hours of an accountant's time pays for itself; monthly bookkeeping is genuinely optional at your scale. More at /guides/bulgaria-freelancer-vs-company-eood.