by Calculated Risk on 10/22/2009 02:52:00 PM

A key point on the impact of the stimulus on GDP ...

From Christina Romer, Chair, Council of Economic Advisers in Testimony before the Joint Economic Committee: From Recession to Recovery

In a report issued on September 10, the Council of Economic Advisers (CEA) provided estimates of the impact of the ARRA on GDP and employment. ...

These estimates suggest that the ARRA added two to three percentage points to real GDP growth in the second quarter and three to four percentage points to growth in the third quarter. This implies that much of the moderation of the decline in GDP growth in the second quarter and the anticipated rise in the third quarter is directly attributable to the ARRA.

Fiscal stimulus has its greatest impact on growth around the quarters when it is increasing most strongly. When spending and tax cuts reach their maximum and level off, the contribution to growth returns to roughly zero. This does not mean that stimulus is no longer having an effect. Rather, it means that the effect is to keep GDP above the level it would be at in the absence of stimulus, not to raise growth further. Most analysts predict that the fiscal stimulus will have its greatest impact on growth in the second and third quarters of 2009. By mid-2010, fiscal stimulus will likely be contributing little to growth.
emphasis added

The impact on GDP will be smaller going forward, and according to Dr. Romer, the impact will be around zero by mid next year, and will be a drag later in 2010 (as stimulus is reduced).