Digital signatures have been a hot topic in the e-government era as a key enabler for e-services provided to business and citizens, and secure exchange of e-documents. When this exchange crosses the borders of closed systems or EU’s Member States, several interoperability issues arise. In EU many schemes and solutions have been proposed to overcome some problems, yet there is still more to be done. This paper provides a survey of the actions taken to promote interoperable use of digital signatures and identifies areas where EU has to invest in order to achieve the desired level of interoperability.