The degree to which this has an effect on the prevalence of informality depends on how easily workers can move between formal and informal jobs and on how much they value other aspects of formal work (including the protection of labour rights other than social security). However, to the extent that markets are competitive, such subsidies can alter the marginal returns of capital, thereby slowing down capital accumulation in more productive parts of the economy. Not only are dual systems that combine job-linked contribution-based social security with a social safety net less desirable from the point of view of social cohesion, they also leave a gap in coverage of middle-income sectors, which enjoy - at best - limited services and - at worst - are excluded, de facto, from both systems by the prevalence of informality.