Using an optimisation based model with endogenous labour supply and a proportional tax rate we compare the stabilising properties of dif-ferent fiscal policy rules. The economy is affected by shocks from both government spending and technology. The fiscal policy rule can be based on government liabilities or the government budget deficit. As both are given as measures of fiscal policy performance in the Stability and Growth Pact (SGP), we also use a fiscal policy rule based on the combination of the two. We compare the accounting definition of deficit with the eco-nomic definition which takes inflation into account. The fiscal policy rule based on debt, wiht monetary policy consistent with the Taylor princi-ple, results in an unstable solut...