The IMF Working Papers series is designed to make IMF staff research available to a wide audience. Almost 300 Working Papers are released each year, covering a wide range of theoretical and analytical topics, including balance of payments, monetary and fiscal issues, global liquidity, and national and international economic developments.
It is well known that the long-run viability of a fixed exchange rate regime imposes constraints on monetary policy. This paper shows that, in a model with forward-looking agents, short-run viability imposes a fiscal constraint. When policy change, which destroys long-run viability, also violates the fiscal constraint, collapse is instantaneous. Delayed predictable collapse requires satisfaction of the fiscal constraint.