Une cible de déficit mouvante est meilleure

Simon Wren-Lewis

"Having a deficit target to be achieved within the next five years, where that five year period remains as time moves on (a rolling target) seems far too easy. There is never a date by which we can unambiguously say that the target has been achieved or not. It would  seem much better to have a target for a fixed date e.g. current balance by 2020.

The problem with this logic comes when we approach 2020, and some unexpected shock occurs. Rather than adjusting to that shock gradually over the next five years, adjustment has to be very rapid. This breaks the first rule of fiscal management, which is that the deficit should be a shock absorber, not a rigid target.

In fact we are used to a similar idea from monetary policy. This attempts to achieve the inflation target within the next two years or so. (In the UK this two years used to be set in stone, but less so now.) The reason often given for this is that it takes some time for changes in interest rates to have their full influence on prices, but this is only part of the story. Interest rates have some impact on prices quite quickly, so it would in principle be possible to try and meet an inflation target with a shorter time horizon, but the reason this is not attempted is that it would lead to damaging variability in interest rates and output."