IV Macro Policy & Sovereign Debt
Fiscal rule
A durable constraint on fiscal policy that sets numerical limits on budgetary aggregates such as the balance, debt, spending or revenue.
How it works
The IMF defines a fiscal rule as a lasting constraint on fiscal policy imposed through numerical limits on budgetary aggregates. The aim is to correct distorted incentives and contain the pressure to overspend, particularly when times are good.
The IMF dataset distinguishes four types. Budget balance rules cap the deficit, debt rules cap the debt stock, expenditure rules cap spending growth, and revenue rules govern the level or use of revenue. Governments often run several at once.
A rule on the statute book is not a rule in force. The IMF states plainly that its dataset records de jure arrangements and does not measure how effective rules are or whether they are honoured. Escape clauses, coverage and correction mechanisms are recorded separately, and they decide how much bite a rule really has.
Why it matters here
Markets do not ask whether a country has a fiscal rule; they ask whether it will hold. After Lula's victory on 26 October, Brazil's January 2031 rate jumped 254 basis points while Mexico's CDS barely moved. Debt ratios did not separate the two. Credibility did. With global benchmark yields stuck near 5%, that credibility gap now sets the extra cost of emerging-market debt.