Social security matters between EU member states are governed by Regulation (EC) No. 883/2004 of the European Parliament and of the Council on the coordination of social security systems and by Regulation No. 987/2009. Among other things, the two regulations deal with posted workers’ social security issues, i.e. paying social contributions in only one member state during their posting according to an A1 certificate. The two regulations will cease to apply to the UK from 29 March 2019, the announced date of Brexit, calling for an evaluation of Latvia’s future cooperation with the UK on social security matters, i.e. whether Latvia will continue to apply A1 certificates to Latvians working in the UK. Since the National Social Insurance Agency (NSIA) has yet to issue an explanation of how Latvia will be handling this issue, let us evaluate the approach taken by other member states and explore Latvia’s options.