"The High Court struck down Sandwell Council's policy of refusing a council tax reduction to anyone who had not lived in the area for at least two years. In a judgment highly critical of the Council, Mr Justice Hickinbottom ruled that the two year residency rule was unlawful on eight separate grounds. The Council acted outside its statutory powers, the two year rule is irrational and discriminates on grounds of race and gender and the Council failed to hold any consultation or comply with its equality duties. The judgment means other Councils who have adopted minimum residence rules will have to review their policies".
http://www.cpag.org.uk/content/council-tax-reduction-minimum-local-residence-rule
http://www.bailii.org/ew/cases/EWHC/Admin/2014/2617.html
http://new.hbinfo.org/forums/topics/no-cts-unless-resident-borough-5-years
is the discussion on this on hbinfo