Should a government have more than one fiscal rule constraining fiscal aggregates? If so, why? In this paper, we present a dynamic general equilibrium model of a small open economy featuring an incumbent government to assess how and why implementing a budget balance rule and a debt anchor rule is non-redundant and welfare-improving. Our findings suggest that the implementation of a combination of fiscal rules is optimally preferred over a single rule, as each rule has a different effect on credibility and fiscal behaviour. While the debt anchor rule prevents the propagation of the negative effects of imperfect fiscal credibility, the operational rule reduces amplification by avoiding overindebtedness and minimizing the welfare-detrimental effects arising from a deficit-biased government.