The European Union (EU) has sought to build a comprehensive immigration policy in which legally residing non-EU nationals, referred to as third-country nationals (TCNs), should be treated fairly and in a non-discriminatory manner. However, a number of gaps and barriers in the legislation adopted can still be identified. This concerns notably the lack of incorporation and implementation of international and EU human rights as well as labour standards. Different treatment between TCNs and further barriers lead to missed opportunities (so to an unoptimal situation) which lower revenue collection for individuals and for society (via taxes). Further EU action in this area could address these gaps by reinforcing existing standards and ensuring a better implementation of immigration policies.