Insurance guarantee schemes (IGSs) provide last-resort protection to policyholders when insurance companies are unable to fulfil their contractual commitments and become insolvent. At present, only a few EU countries have one or more IGSs in place and their national schemes diverge from each other. This document, prepared by JRC for FISMA, is a quantitative assessment of several policy options for a possible proposal on the introduction of harmonized rules for IGSs. The document presents a parsimonious credit risk model which can use aggregate insurance data to estimate the loss distribution and funding needs of IGSs under different policy options regarding scope, nature of intervention and coverage. The results provide estimates of the levels of coverage that can be reached in each policy setting under different choices of funding levels. This report is a follow-up of previous studies on IGSs developed by JRC in 2010 and 2014. For any given level of security, results appear to be dependent on the level of the Probability of Default of insurers, and show variation across countries following the variation in the level of Exposure at Default. Robustness checks are conducted to check the stability of results, notably through time.