The European Union is moving to resolve one of the most unusual and sensitive issues in the enlargement process: Montenegro’s long-standing use of the euro without formal membership in either the EU or the eurozone. What was once tolerated as a stabilisation measure is now emerging as a technical and legal obstacle at the most advanced stage of accession negotiations.
Montenegro has used the euro unilaterally since 2002, without any formal agreement with the European Central Bank or the EU framework. This arrangement—known as “unilateral euroisation”—falls outside EU treaty rules, which require candidate countries to first join the Union and then meet strict convergence criteria before adopting the common currency.
As accession talks move toward closure, this anomaly is becoming harder to ignore. According to Montenegro’s finance minister Novica Vuković, the European Commission is actively working on a “pragmatic solution”, with a formal proposal expected by the end of May.
The issue is not political in the traditional sense; it is institutional. EU accession rules have never had to accommodate a country that already uses the euro for decades without being part of the eurozone. That creates a legal gap: Montenegro cannot formally “adopt” the euro through the standard pathway because it already uses it, yet it does not meet the formal criteria required by EU treaties.
At the same time, reversing euroisation is not a realistic option. The euro underpins Montenegro’s financial system, banking stability and external credibility. The country has no independent currency, and its central bank operates without monetary sovereignty, relying effectively on eurozone monetary conditions.
This leaves Brussels with a narrow set of options. One path under discussion is a formalised recognition mechanism, effectively legitimising Montenegro’s euro use within the accession treaty framework without forcing a disruptive transition. Another possibility involves transitional arrangements tied to fiscal discipline, financial supervision and alignment with eurozone governance rules.
The timing is critical. Montenegro is currently the most advanced EU candidate, with 14 negotiating chapters provisionally closed and a target accession horizon around 2028. The EU has already begun drafting the accession treaty, marking a shift from negotiation to execution. Any unresolved institutional issue—especially one tied to monetary policy—risks delaying the final stages.
Beyond legal technicalities, the euro question carries deeper economic implications. Montenegro’s unilateral euroisation removes currency risk, lowers borrowing costs and anchors investor confidence. At the same time, it eliminates traditional macroeconomic tools such as exchange rate adjustment and independent monetary policy, placing greater pressure on fiscal discipline and external balance management.
For Brussels, the challenge is to reconcile legal consistency with geopolitical momentum. Enlargement policy has regained urgency, and Montenegro is positioned as a test case for accelerating accession in the Western Balkans. The euro issue, while technical, sits directly at the intersection of treaty law, financial stability and enlargement credibility.
What emerges is a negotiation not about whether Montenegro will use the euro—it already does—but about how that reality is formally embedded into the EU system without setting a precedent that could complicate future enlargements.
