Mergers of local governments, commonly referred to as municipal mergers, have been widely implemented to internalize spillover effects. Many empirical studies point out that municipalities change the intertemporal budget allocation by increasing their debt issuance before mergers and they consider that this debt issuance is induced by the “fiscal common pool problem” because of pooled budgets after mergers. However, this phenomenon has yet to be analyzed theoretically. Therefore, this paper examines the mechanism of increased debt issuance before municipal mergers. We compare the debt issuance in the merger case with the level in the socially optimal and nonmerger cases. We find that the amount of debt issuance is larger in the merger case than in both other cases. The difference vanishes when spillovers are perfect.

地方政府兼并，通常称为市政兼并，已被广泛实施以内部化溢出效应。许多实证研究指出，市政当局通过增加合并前的债务发行来改变跨期预算分配，他们认为这种债务发行是由合并后的合并预算导致的“财政共同池问题”引起的。然而，这种现象还有待从理论上进行分析。因此，本文考察了市政兼并前增加债务发行的机制。我们将合并案例中的债务发行与社会最优和非合并案例中的水平进行了比较。我们发现，合并情况下的债务发行量大于其他两种情况。当溢出完美时，差异就消失了。