The Institute of Fiscal Studies note:

Because the proposed uprating changes apply to almost all benefits and tax credits, both in-work and out-of-work households are affected. Of 2.8 million workless households of working age, 2.5 million will see their entitlements reduced, by an average of about £215 per year in 2015 –16. Of 14.1 million working-age households with someone in work, 7.0 million will see their entitlements reduced, by an average of about £165 per year. Note that this figure includes 3.0 million families who lose only from the cuts to Child Benefit, at an average of about £75 per year (monetary amounts are in current prices). 

http://www.ifs.org.uk/publications/6539  for the full note