The Covid 19 pandemic has caused both a decrease in tax revenues and an increase in public spending, forcing governments to increase fiscal deficits to unprecedented levels. Given these circumstances, it is foreseeable that fiscal rules will play a predominant role in the design of many countries¿ recovery policies. We develop a general equilibrium, overlapping generations model for a small, open economy in order to study the impact of several fiscal rules upon welfare, public expenditures and growth. We calibrate the model to the Peruvian economy. In this economy, fiscal rules have been widely used and, unlike in other Latin American countries, they have been relatively successful. We find that fiscal rules will generate better results in terms of output if, in addition to maintaining control over the fiscal result, they also preserve public investment. We also find that the performance of economies that implement structural rules tends to be better than the performance of economies that implement rules based on realized budget balance., Jose E. Galdon-Sanchez acknowledges financial support from Spanish State Research Agency through project PID2021-127119NB-I00 and by “ERDF A way of making Europe”. Julián Díaz-Saavedra acknowledges financial support from the Spanish State Research Agency through project PID2019-110783GB-I00/AEI/10.13039/501100011033. Open access funding provided by Universidad Pública de Navarra.

We consider the problem of cleaning a transboundary river, proposed by Ni and Wang (Games Econ Behav 60:176–186, 2007). A river is modeled as a segment divided into subsegments, each occupied by one region, from upstream to downstream. The waste is transferred from one region to the next at some rate. Since this transfer rate may be unknown, the social planner could have uncertainty over each region’s responsibility. Two natural candidates to distribute the costs in this setting would be the method that assigns to each region its expected responsibility and the one that assigns to each region its median responsibility. We show that the latter is equivalent to the Upstream Responsibility method (Alcalde-Unzu et al. in Games Econ Behav 90:134–150, 2015) and the former is a new method that we call Expected Responsibility. We compare both solutions and analyze them in terms of a new property of monotonicity., Jorge Alcalde-Unzu acknowledges the financial support from the Spanish Government through projects PGC2018-093542-B-I00 and ECO2017-91589-EXP. María Gómez-Rúa acknowledges the financial support from the Spanish Government through projects ECO2014-52616-R and ECO2017-82241-R and the Galician Government through projects GRC 2015/014 and ED431B 2019/34. Elena Molis acknowledges the financial support from the Spanish Government through projects ECO2015-67519-P and PID2019-110783GB-I00, the Basque Government through project IT-568-13 and the Andalusian Government through the projects SEJ1436 and SEJ492.