Foreign workers often lack the proper permits to legally declare income in the state where they are employed. In these cases, declaration of their income could have consequences ranging from the imposition of fines to deportation.
Undeclared workers are usually ill-paid, have low-quality jobs and do not benefit from social security or dismissal protection and do not receive the training regularly employed workers receive. The great majority of undeclared workers are illegal immigrants.
(adapted from European Union,
Employment, Social Affairs & Inclusion, visited 2009-05-15)