This study provides a quantitative assessment of the potential impacts of the
formation of a COMESA customs union, specifically of having free trade among
COMESA countries while imposing a common external tariff against imports from
outside COMESA. The study uses an expanded version of the Global Trade Analysis
Project (GTAP) database and capitalizes on the Modeling International Relationships
in Applied General Equilibrium (MIRAGE) Computable General Equilibrium (CGE)
model for analysis. Two different assumptions are made regarding the number of
sensitive products excluded from the CET rates—2 percent or 5 percent. The
simulation exercise involved four scenarios to compare the impacts of the customs
union under two alternative specifications of sensitive products, and the impacts of
three alternative membership assumptions on the COMESA region. The alternative
COMESA customs union scenarios are designed at the detailed Harmonized System
at the six digit level (HS6), combining information on the current applied protection
from the 2004 MAcMap data base and the COMESA Tariff Nomenclature.
Nzuma, J., Gbegbelegbe, S., Massawe, S., and J. Karugia. 2009. A Quantitative Assessment of the COMESA Customs Union. ReSAKSS Working Paper 30. Washington, D.C.: IFPRI.