Should Bulgaria wait for 90% real convergence before joining the Eurozone?

In the lively public policy debate in Bulgaria on the country joining the Eurozone, a claim is being made that real convergence of at least 90% is a crucial precondition for joining and therefore Bulgaria should wait until the early 2040s, because only then it is expected to achieve such convergence. The claim is supported with theoretical arguments, empirical evidence and forecasts. Here they are examined in some detail in the context of Bulgaria’s unique position as a country in the EU with a Currency board regime anchored in the euro. It is concluded that economic theory does not pose a requirement for any level of real convergence for an economic area to join a monetary union. In theory, problems due to a less-rich country joining a more affluent monetary union may, but also may not, cause problems such as excess inflation or amplified business cycle. It is also concluded that neither the claim that there exists a convergence threshold of 90% of real income per capita, nor the claim that Bulgaria will necessarily need at least two decades to reach it can withstand even most elementary checks for empirical robustness. Both the theoretical and the empirical claims that Bulgaria should wait for a 90% real convergence until at least the early 2040s before joining the Eurozone are found to have no real economic foundation.