The European Commission has decided to refer the United Kingdom to the EU's Court of Justice because it is in breach of EU law
The Commission is doing this because the UK fails to apply the 'habitual residence' test to EU nationals who reside in the UK and claim social security benefits.
Instead, the UK applies a so-called “right to reside” test, as a result of which EU citizens cannot receive specific social security benefits to which they are entitled under EU law such as child benefit.
For more information see the European Commission press release.
According to the BBC Iain Duncan Smith said he planned to fight the commission "every step of the way".
The right to reside and habitual residence tests are used throughout the benefits system, including the new personal independence payment. You can find more about how they apply in our factsheets.