Special Cases: International going to or coming from abroad EEA Regulations 883/04 (After 1 May 2010): Normally working in two or more Member States
Article 13 (1) of Regulation 883/2004 of the European Parliament and of the Council of 29 April 2004 on the coordination of social security systems
Article 14 of Regulation 987/2009 of the European Parliament and of the council of 16 September 2009 laying down the procedure for implementing Regulation (EC) No 883/2004 on the coordination of social security systems
NIM33035 explains the general rule that you contribute where you work
NIM33065 explains the important exception for workers posted temporarily to another Member State.
Another important exception to the general rule in Article 11.3(a) applies to workers with a working pattern in which they normally work in two or more Member States. Where under the special rules in Article 13 such a worker is subject to United Kingdom legislation, then the worker, and their employer(s), will pay UK National Insurance contributions. The total earnings that the worker receives from working in the different Member States is taken into account when calculating how much UK National Insurance contributions is due.
A person working in the UK who claims to be exempt from UK National Insurance under this rule should be able to produce a Portable Document (PDA1) issued by the authorities in the Member State they have come from as proof of this exemption.
If they do not then UK National Insurance contributions will be due until they produce the Portable Document A1.
You should give the worker a reasonable amount of time to produce a PDA1. A delay of several months is not uncommon for the other Member States to issue the form
(This content has been withheld because of exemptions in the Freedom of Information Act 2000)
You can read more about the rules at NIM33020