Such flexibility is best provided via the so-called automatic stabilisers: revenues and spending can vary in a proportionate and smooth way throughout the economic cycle, while deficits and surpluses should broadly balance each other out in the course of time.
A balanced budget over the medium term not only contributes to the sustainability of public finances but it also allows fiscal policy to play an output-stabilising role. We sometimes hear these days siren songs about abandoning the Pact, so as to “give growth a chance”, as if policy makers were confronted with a choice between stability and growth.