The adoption of a common central Bank has modified the strategicrelationships between fiscal and monetary authorities and raised in a newcontext the issue of debt stabilization. To study this problem, Van Aarle et al (1997) have proposed a two-country model with acommon central bank. In a sense they obtained a neutrality result: theadoption of a common central bank does not modify the evolution of debt ifthe authorities can commit. This note reexamines this neutrality result bydeparting from the previous authors on three points: i) externalities areintroduced between countries to account for the elasticity of the worldinterest rate to macro-economic policies, ii) the model features n countries, some of them remaining outside the monetaryUnion, iii) analytical results are given (many results of Van Aarle et al (1997) were numeric). In this extended context theneutrality result collapses: i) the institutional change introduces anasymmetry between countries, ii) countries inside the monetary union improvetheir long run welfare, iii) but the outside countries can win or lose underthe new institutional setting.