The generational accounting approach (Auerbach and Oreopoulos, 1999, 2000; Lee
and Miller, 2000; Fehr et al., 2004) attempts to project forward from the characteristics
of current migrants to a more accurate assessment of the present discounted value of
lifetime fiscal contributions. Doing so requires an accurate knowledge of future
earnings paths, future return decisions and future paths of tax and welfare systems and
to that extent the approach is unavoidably and arguably dangerously ambitious in the
assumptions it needs to rely upon.