"Net migration" refers to the difference between the number of people who move into a particular country or region and the number of people who move out of it. Full definition
The coalition is unlikely to meet the coalition's net migration target in 2011, when the total is expected to exceed 200,000. (politics.co.uk)
If the government is to achieve its target of net migration in the tens of thousands by the end of this parliament, they must tighten the system across the board. (politics.co.uk)
This is one of the ways we will reduce net migration back to the levels of the 1990s — tens of thousands not hundreds of thousands. (channel4.com)