Back to overview


As of 01/01/2021, the transition period under the EU’s withdrawal agreement will end and the fundamental principles of free movement – persons and services – will no longer apply in the United Kingdom. However, specific social security rules will apply to situations that have already started before the end of 2020.

Existing cross-border situations, which have already started before the end of 2020

The applicable social security system will continue to be determined by the European Regulation 883/04 as long as the cross-border situation is uninterrupted and has already started before the end of 2020.

However, certain situations are assimilated to “uninterrupted” situations such as sickness, career break with benefits, annual leave, …

Any other interruption, regardless of the duration, will in principle terminate the Brexit exit rights (Article 30, paragraph 2 of the withdrawal agreement WA), with the result that the relevant EU law will no longer take effect, but the national law of the member state concerned will take effect.

Different types of cross-border situations can follow each other seamlessly without jeopardising these exit rights. An A1/E101 certificate can be issued in each case.

 Cross-border situations starting from 2021

If the situation does not start until after the end of the transition period (31/12/2020) or is interrupted, the national law of the member states concerned will take effect. It is therefore possible that a worker will not be insured anywhere or will have to pay social security contributions on the same salary in both countries.

The UK is to be considered entirely as a “third state” and its nationals as “third country nationals not belonging to the European Economic Area”.

1. Posting UK ► BE

Article 3 of the Belgian Social Security Act (NSSO) stipulates that an employee is only subject in Belgium if he is employed on Belgian territory by an employer established in Belgium (or is attached to a Belgian operating office of an employer established abroad).

In the case of posting (i.e. exclusive employment relationship with a UK employer), the worker concerned will not be subject to the Belgian employment system, regardless of the duration of the employment in Belgium. In this case, the NSSO may issue an “Article 3 declaration” giving advice on the non-fulfilment of the conditions.

The worker can continue to be insured for 52 weeks in the UK scheme if certain conditions are met.

2. Posting BE ► UK

A worker posted from Belgium remains subject to the employment system for a maximum period of 6 months, renewable for a maximum period of 6 months. There is no possibility to derogate from this for a longer period. An interruption of at least 2 months is necessary to set the “counter at zero” and to grant a new period. The NSSO can issue a document K/TM 138ter on request.

Voluntary affiliation to the Belgian system of the Overseas Social Security is possible when working in the UK.

The worker can be exempted from being subject to the UK scheme for 52 weeks if certain conditions are met.

3. Employment in several member states and one aspect in the UK

In these situations (e.g. employer in the UK, part of the work in the UK, …) all aspects of the case must be examined on a case-by-case basis.

In the case where the only link with the UK is the nationality of the worker, the regulations will apply and the member state of residence or the member state where the employer is established will be authorised for its social security. An A1 certificate will be issued by that member state.


Source: Newsletter International Relations (NSSO)


© Van Havermaet International 2024

We use cookies or similar technologies (e.g. pixels or social media plug-ins) to optimise your user experience on our website, among other things. In addition, we wish to use analytical and marketing cookies to personalise your visit to our website, to send targeted advertisements to you, and to give us more insight into your use of our website.

Do you consent to our use of cookies for an optimal website experience, so that we can improve our website and surprise you with advertisements? Then confirm with ‘OK’.

Conversely, would you like to set specific preferences for different types of cookies? This can be done via our Cookie Policy. Would you like more information about our use of cookies or how to delete cookies? Please read our Cookie Policy.