To evaluate the spatialities of the illegal wage practice where employers pay their declared employees both an official declared wage and an undeclared ‘envelope’ wage so as to avoid tax liabilities, a 2007 survey conducted in 27 European Union (EU) member states is reported. The finding is that 5% of employees received envelope wages which amount on average to some two-fifths of their wage packet. Revealing how, although heavily concentrated in a small group of East-Central European nations, this wage practice is nonetheless ubiquitous, the paper concludes by discussing how this practice might be tackled.