Mr. James Murunga on Wednesday 27th April 2022 successfully defended his PhD in Economics Thesis.  

The thesis is titled : Review of Dissertation on Essays on the Size of Kenya’s Informal Sector, Tax Productivity

and Optimal Tax Ratio

The Department congratulates Mr. Murunga on this academic milestone achievement. 


In Kenya very little research has been carried out on the effect of the size of the informal sector on tax
performance. Failure to raise adequate tax revenue from the increasing informal sector implies the
government should either resort to unpopular tax rates increases or public debt.


Each of these approaches has ramification on the economy. To come with relevant policies, it is important to
understand the link between size of the informal sector and tax revenue performance. This paper
estimates the effect of the size of the informal sector on tax revenue performance in Kenya for the
period 1970-2018. On testing for stationarity, the study establishes a mixture of I (0) and I (1) variables
thus suggesting the use of Autoregressive Distributed Lag model.

The finding indicates that the size of the informal sector negatively influences tax revenue in Kenya. This implies that the informal sector’s output may be increasing but little tax is generated from it. The finding also has implications for the
conduct of the Kenya Revenue Authority (KRA). To reduce the size of the informal sector, KRA should
increase surveillance to identify economic activities that fall within the tax bracket and tap tax revenue
from them.