The Prime Minister tweeted that today was a "big day for welfare reform" as a benefit cap pilot begins in four London boroughs.
A big day for welfare reform as we pilot a cap on benefits equal to the average wage. Amazingly Labour oppose it.
The changes mean couples (with or without children) and lone parents will be limited to £500 and single adults capped at £350 per week in total benefits.
For much more details on who is affected and which benefit payments are included, read: What is the benefit cap?