As the transition period ends, the #BrexitDeal applies from tomorrow. But there's also a parallel significant legal change - most of the rest of the withdrawal agreement starts to apply. A thread on the legal issues in the rest of that agreement.

The citizens' rights provisions of the withdrawal agreement (on EU citizens who moved to the UK, and UK citizens who moved to the EU, before the end of the transition period) start to apply.

Annotation and detailed analysis of those provisions here:

After today, UK citizens newly moving to the EU, or EU citizens newly moving to the UK, are in principle governed by national law (partly harmonised by the EU, on the EU side).

However, the #BrexitDeal contains some provisions on visas for service providers.

The #BrexitDeal also refers to the matching unilateral decisions of the EU and UK to waive a visa requirement for short tourist visits. Analysis of the EU law on that issue here:

UK citizens resident in the EU on the basis of the withdrawal agreement (or who move to EU in future) should be covered by the EU law on long-term resident non-EU citizens, which provides for a limited form of mobility between Member States. Analysis here: