In Sweden, unlike for example Norway, problems associated with people "falling between the cracks" and ending up outside the welfare systems has not led to extensive restructuring of the social insurance system. Instead, in many cases, cooperation between authorities and responsible actors is emphasized as a means to prevent social and economic exclusion. Since 2008, cutbacks in Swedish sickness benefits has increased the proportion of job seekers with weak ties to the labour market, thus also increasing the number of individuals potentially subject to such cooperation. However, our study shows that those denied of sickness benefits, as the Social Security Agency considered them capable of working, will not in all cases be eligible for unemployment benefits. One reason is that different work ability concepts apply, where the assessment of the right to sickness benefits is characterized by the purpose to insure those unable to work due to sickness, whilst the corresponding assessment in the unemployment insurance is characterized by the purpose to insure those who are able to work. It also shows that a clear assessment of the overlap between these respective work ability concepts is made difficult, especially due to unclarities regarding what constitutes work ability in the unemployment insurance. Therefore, the design of the insurance systems affects the potential to reduce exclusion through cooperation, and poses challenges to legal security for those in transition between the systems and to a well-informed management of insurance policies.