Housing benefit will no longer cover the housing costs of private renting, workless families with 3 or more children anywhere in London.
For low-income single adults without children, a third of London's boroughs (34%) are unaffordable under the welfare reforms.
Demand for the cheapest properties means that even 13 of London's 19 outer boroughs are unaffordable for families reliant on housing benefit.
More top news
London mayor Sadiq Khan is "extremely worried" about knife crime as Met Police revealed there was an increase in stabbings in the capital.
Camden police have responded to reports of an unexploded World War Two bomb in Hampstead high Street.
AFC Wimbledon face Plymouth in the League Two play-off final at Wembley, with a place in League One at stake.