The Effect of Monetization on Tax Buoyancy: Evidence From COMESA Using A Panel Data Analysis


Countries in Commonwealth Market for Eastern and Southern Africa (COMESA), like many other developing nations face difficulty in raising tax revenue for public purposes. This study uses panel data analysis for nineteen countries during 2000-2009 to analyze empirically the determinants of tax buoyancy. Among the variables identified as affecting annual tax buoyancy is monetization, with empirical results confirming its importance. The results have shown that the way monetization is handled in the developing nations affects annual tax buoyancy negatively. Other variables that have been found to be affecting tax buoyancy include the growth in the agricultural and industrial sector contribution to national income, external aid growth, growth of fiscal deficit and growth of total expenditure. The determinants of tax buoyancy have been suggested following tax handle theory advice. The study yielded such results because quality dimension of tax performance have been considered, which has been neglected by many previous authors.



The traditional function of the tax system is to bring in sufficient revenue to meet the growing public sector requirements. Common measures of the ability of the tax system to mobilize revenues are buoyancy and elasticity (Asher 1989). A desirable property of a tax system is that income elasticity and buoyancy should be equal or greater than unity. Such property ensures that revenue growth keeps pace with that of Gross Domestic Product (GDP) without frequent discretionary changes. More important, it imparts build-in stability to the tax system, hence ensuring mitigation of cyclical variations in GDP over the course of the business cycle.

Concentration of the study will be on tax buoyancy, which indicates whether the tax “keeps up” with growth in the economy. Tax buoyancy measures the total response of tax revenue to changes in national income (Begum, 2007). Year to year buoyancy measures the volatility of the tax and the ability of government to meet the demands of their constituents. As an economy grows, income of taxpayers grows and the demand for public services tends to increase. If tax revenues grow less quickly than the economy, then the public sector will not be able to meet increased demand for better social amenities.

The Commonwealth Market for Eastern and Southern Africa (COMESA), in line with the above indicator (buoyancy), comprises of low tax performance countries with average regional buoyancy that is less than unity (Matshediso, 2004) implying that the tax system is not responsive to the income changes in the region. An effort to improve tax performance has been done over the years mainly noted by various reforms in the taxing system but no significant permanent solutions have been reaped so far. On the other hand, policies relating the monetization to tax performance have not yet received attention in the region.

The study attempts to examine the determinants of tax buoyancy, paying particular attention on the effect of monetization on tax buoyancy. The tax performance analysis aims at finding out whether there is a possibility of increasing tax revenue in developing nations through the monetary policy. Taxation is an important instrument for attaining a proper pattern of resource allocation, income distribution, and economic stability, in order that the benefits of economic development are evenly distributed.

Tax systems should be adequately stable and buoyant in order to enable a country to meet its increasing financial commitments as its gross domestic product (GDP) grows. If the tax revenue of a country is stable and buoyant, there is a high probability that its public expenditure needs will be adequately met over time. If GDP is growing more than tax revenues then it could be one policy indicator that the tax structure needs reform. The study of tax buoyancy is of much importance because it is both a quality and quantity measure of tax performance. Tax buoyancy can also be used to summarize revenue growth over time, (Zolt, 2003:8). Finally, it shows the strength of the tax system in the country when they are subjected to certain environments for example when a certain sector is declining.

The manner in which different countries raise taxes differs as widely as do the amounts they raise. The pattern of taxes found in any country depends upon many factors such as its economic structure, its history, and the tax structures found in neighbouring countries (Bird and Zolt, 2003: 7). According to Zolt (2003:1), developing countries are no different: ideas, interests, and institutions play a central role in shaping tax policy. Basing on this argument the study will be focusing on COMESA countries since they are close to each other and belong to a community. Countries no longer have the luxury to design their tax systems in isolation.

The research problem is derived from the fact that public services in the past years in developing nations have been deteriorating. The level of revenue being raised from taxation is very low in these nations as compared to the tax base which shows their tax potential. Rapid expansions in expenditure and declining or low revenue levels have been the main cause of fiscal imbalances in COMESA countries over the years (Ghura, 1998).

Tax revenues appear to be highly volatile relative to GDP, the tax base (Ghura, 2004; Greenaway, 2005). According to Ghura(2004), the changes include the effects of changes in tax rates, deductions and compliance. Developing countries are characterized by high tax rates (exorbitant tax rates, Matshediso 2004) as compared to developed nations, the obvious effect being decreasing tax revenues collection due to the increased informal sector activities and hence the governments are not able to meet public demand of public goods. The existing persistent budget deficits in developing nations suggest that the tax system is not revenue productive, and in such situations increasing revenue should be the main objective of tax policy.

On the other hand money supply in the COMESA economies has been growing at high levels but has been named inflationary. There are high levels of tax erosion, due to high growth of money supply (RED, 2006). Given the continuous reforms (leading to uncertainty and loss of credibility) that have been happening in the taxing system of developing nations, it still remains a wonder why tax performance is still low and even declining in some countries. The monetary sector has not received attention as far as taxing policies are done in these nations and hence its emphasis should be brought about, since some studies have proposed its importance.

The objective of the study is to establish the main determinants of tax buoyancy in developing countries with special attention to the effect of monetization on the tax buoyancy. The General and Specific research questions of the study can be stated consecutively as follows: What are the main determinants of tax buoyancy in developing nations? How does monetization affect tax buoyancy? The main hypotheses to be tested in this study are that: Monetization have a positive relationship with tax buoyancy. Growth of the industrial sector and agricultural sector, fiscal deficit, external debt, level of economic development, total expenditure and trade openness increases tax buoyancy. Growth in external aid and the concentration of population reduces tax buoyancy.These hypotheses are tested by determining the significance of the regression coefficients of relevant regression equation that will be estimated.


Countries no longer have the luxury to design their tax systems in isolation due to current wave of globalization and regionalization (Bird and Zolt, 2003).  With dramatic reduction in trade barriers over the last two decades, taxes have become a more important factor in location decisions. There is increased tax competition for portfolio investment, qualified labor, financial services, business headquarters and foreign direct investment. This means that taxes do matter, and any country with a tax system that differs substantially from other countries, particularly its neighboring countries, may suffer. From this idea, analysis of determinants of tax buoyancy in the SADC region can be undertaken, since the countries trade with each other, share labor services and share national borders.

The previous studies (Harley(1965), Lotz and Morss(1967), Raja(1971), Raja et al.(1975) and Roy(1979)) of tax performance have been dwelling much on quantitative measures of tax performance such as the tax ratio. There is a need to incorporate both a quality and a quantity measure of tax performance, in this case tax buoyancy. There are few studies (for example Teera, 2002 and, Bird and Zolt, 2003) carried out in this area especially for African countries. It is a new area which needs further investigation around the regions of the world. Also the study involves the determination of yearly buoyancy, of which several studies (Quazi(1994), Begum(2007) and Teera(2002)) have been involved in the use of single averages over a period. The main base of this study’s approach is that tax buoyancy changes over time even annually because of many factors (discretionary changes) which may include the political environment among others.

The effect of monetization on tax buoyancy is a crucial issue to consider when making tax performance decisions. This is because policy makers have to critically administer the optimal level of money supply in the economy that will not have adverse effects on economic agents. If money supply grows faster than the growth of the economy, inflation arises and the problem of tax erosion occurs since there is a gap between the time tax are to be paid and when they are actually paid. Increased documentation of the economy can also arise as monetization increases and hence this facilitates the collection of both direct and indirect taxes. From this idea the impact of monetization on tax buoyancy has to be analysed. The results will be used to give necessary policy advice on the link between monetization and tax performance. The incorporation of money supply in taxing decisions of governments is also a contribution, the variable have been left by many authors without any justification.

The study will contribute to existing literature on tax buoyancy for developing nations, this helps in the continuous debate of the effects of various determinants.  Analyzing the determinants offers a guide to policy makers on which areas to put more emphasis. According to Teera (2002), a poor tax performance, in terms of raising revenues can mean either deficiencies in tax structure policy or an inadequate effort to collect, on the part of government, both of which are influenced by various factors. Hence the study concentrates on finding factors that affect tax performance.

 Therefore there is need for more empirical input and guidance to carry out rational economic decisions. To formulate strategies for achieving sustained increase in tax buoyancy relevant information is necessary. Therefore examining determinants of tax buoyancy is an appropriate way of finding where policies can rightly respond to those issues and as such we would gain better understanding about the determinants. Knowledge of the determinants of tax buoyancy in SADC will help preclude policy makers from (over) emphasizing only few variables to neglect of other important ones in promoting tax performance.

Theoretical and Empirical Literature Review

Theoretically and empirically tax buoyancy can be calculated using the Constant Structure rate, Dummy variable method, Divisia Index and the proportional method. However this study due to its nature will use annual tax buoyancy, as the above methods refers to periodical buoyancy.

The normative bent of the literature on tax policy deals with the questions of why a country develops a particular tax structure and why this tax structure differs among countries and changes during the process of economic growth. This strand of tax literature not only recognizes the importance of administrative constraints on tax policy, but in contrast to the normative literature places administrative factors at the forefront.

The “tax handle” theory offers a sweeping historical explanation of tax structure change. It argues that low-income economies are forced to collect revenue from easy-to-administer taxes (or tax handles), but that this administrative constraint lessens as countries develop and become able to choose “better” taxes as defined by the normative objectives discussed above. Measures of tax handles typically include per capita income, trade taxes and the proportion of people living in urban areas (Liebaman, 2003).

The optimal tax theory, the reigning normative approach to taxation combines information on a country’s economic structure, the set of available taxes to the government and the objectives of tax policy to make recommendations on tax mix, structure and incidence (see Slemrod, 1990; Burgess and Stern, 1993). Optimal taxes are those that raise a desired amount of revenue with the lowest marginal efficient cost, with few distortions and that promote the desired amount of wealth. While optimal tax theory tackles the trade off of different taxes, it does not explain the structure of government revenues.

The Ricardian equivalence theory is based on the opinion that when the government borrows instead of levying taxes to finance budget deficit the current generation is under taxed, they are rational and will realize that the loan will have to be repaid from income tax at some time in the future; debt finance is therefore a postponement of the tax burden which will fall on the future generation. The importance of this theory to tax performance is now questionable given the continuous borrowing done in developing nations and continuous budget deficit in the economies. The theory suggests discipline in the monetary sector and also effective borrowing which does not affect generations to come.

Quazi (1994) carried out a study of the determinants of tax buoyancy in developing nations using 35 countries for a period of ten years. The countries were chosen at random all over the world but based on the level of national income. Zambia and Zimbabwe are the only COMESA countries that managed to be selected. He used the ordinary least squares method in the regression of tax buoyancy and its suggested explanatory variables. The model includes average growth of money supply (monetization- M2), import sector output, industrial sector output, service sector output, agricultural sector output, deficit, grant and Gross Domestic Product (GDP). He found monetization to be positively related to tax buoyancy, he commented that an increase in monetisation increases the documentation of the economy which increases tax collection. His conclusion was that increase in the level of monetization through increase in documentation also facilitates the growth of taxes. Other variables found to affect buoyancy include growth of industrial sector, growth of imports and growth of grants.

A study by Begum(2007) of the determinants of tax share and revenue performance (buoyancy) is worth noting. The study of Bangladesh along with ten other developing countries through a panel data analysis span for fifteen years. The results obtained suggest international trade, broad money, external debt and population growth to be significant determinants, with expected signs of the estimated coefficients. The study identifies Bangladesh as the lowest tax effort country in the sample, with an average tax effort index of 0.493. This has important policy implications that Bangladesh and other countries having low tax effort (less than unity) are not utilizing their full capacity of tax revenue, and therefore, have the potential for financing budgetary imbalance through raising tax revenue.

A study carried out by Teera (2000) found that the results of the dynamic measure of tax performance (tax buoyancy) indicate that the high-income OECD group has the least percentage number of countries with a buoyancy ratio below unity, followed by the lower middle-income group. This implies that the lower income groups have made less effort to increase tax revenues over the period as compared to the higher income groups. He mainly hammered on the tax evasion variable. In his regression he included variables like total expenditure and also time trend.

Methodology and Data Analysis

In the hope to improve tax performance COMESA countries have been undertaking several reforms either individually or collectively. The shift from Sales tax to Value added tax (VAT) has seen many countries improving their tax collections and reducing tax burdens of the tax payers. During the period under study VAT has dominated Sales tax and is in use. Furthermore nations have launched Autonomous and semi-Autonomous Revenue authorities (SARAs) to have the duty to collect revenue on behalf of the government. This was done to separate political influence and revenue collection. However the efficiency of these SARAs is debatable, revenue have been seen rising in the few years of introduction of SARAs then they decline.

Panel data methodology is used in the analysis since cross-sectional and time series are combined. The methodology is more common for the comparison of different countries. Nineteen countries in the COMESA region are considered over a sufficient period. Data for analysis is obtained from the African Development Indicators various publications and World Bank/IMF publications. The advantage of these sources is that they allow international comparisons to be made.

Using various theoretical literature and empirical literature many variables have been identified as affecting tax buoyancy. The main variables to be used in the study include monetization, level of economic development, structure of the economy (contribution of agriculture and industrial sectors to GDP), external aid growth, debt, population size, expenditure growth and trade openness.

The following results have been found after regressing tax buoyancy against its determinants using STATA econometric software. Multicollinearity and homoskedasticity have been checked. Panel tests have been done and the best model was the pooled Ordinary least Squares (OLS) and time effects have been taken into account.

Specific Pooled OLS Model [Dependent Variable BUOY]

        BUOY                    Coef.                      Std. Err.                        P>|t|    

        ECON                   .0055117                .0040867                         0.179   

         AGR                     .0188142                .0071365                         0.009***   

         IND                       .0219473                .0067639                         0.001***

          MS                      -.0043354                .001639                          0.009***

         AID                      -.7558855                 .1211132                        0.000***  

          DF                       -.0165895                .0064552                         0.011**  

          XM                       .0056362                 .0044746                         0.210   

         EXP                      .8653563                  .3776645                         0.023**    

        Trend                   -.074938                    .035562                          0.037**

       _cons                    150.7422                 71.12115                          0.036**

R-squared     =  0.4063         Adj R-squared =  0.3725

F =   12.01          Prob > F      =  0.0000***         

* denotes statistical significance at 10%, ** at 5% and ***at the 1% level

Discussion of Results

The F statistic 12.01 (0.0000***) shows that the model is correctly specified and that the null hypothesis of variable inclusion is rejected at the 1% level of significance and we therefore conclude that at least one of the variables in the model explain the magnitude of annual tax buoyancy in COMESA economies.

The coefficient of monetization (MS) has a negative value and significant at the 1% level indicating that growth of money supply (M2) seems to negatively affect the tax buoyancy of COMESA states. The results are not in line with the tax handle theory which poses for a positive sign. This means that the growth of money supply does not facilitate the documentation of the economy so as to improve tax administration. The reasons why monetization has a negative influence on tax buoyancy in the COMESA region might be due to the lack of capacity within the tax administrators to take advantage of the growing supply of money to facilitate the tax collection of each tax, over relying on printing money to finance government activities rather than generating revenue elsewhere, the presence of distortions such as trade barriers, weak legal and financial systems. Some COMESA financial markets are not well developed. The region has a narrow range of intermediaries and offers a limited number of financial instruments. This finding is not in line with the result obtained by Quazi (1994) who found a positive and significant effect of monetization and tax buoyancy for a sample of 35 developing countries in a period of 10 years. Begum (2007) obtained a positive significant coefficient for Bangladesh which is a developing nation, the reason being that there is utilization of growing money supply to facilitate the documentation of the economy.

The coefficient of growth of the agricultural sector (AGR) is .0188142, with a p-value of 0.009 showing that the coefficient of domestic investment was positive and significant at 1% level. Thus countries that are able to maintain and improve their agricultural sector will experience an increase in their tax performance. 

Growth of the industrial sector (IND) has a positive and significant impact on tax buoyancy at all levels of significance. This shows that it is one of the major variables that explain how the tax system is performing in developing nations. This is in line with the tax handle theory which predicts a positive impact. The possible reason for such results is that the sector is easy to tax, companies keep records of transactions and many are located in urban areas which reduces costs of tax collection. Industry includes mining companies which are very large and also few and hence easy to monitor and audit for tax payment.

External aid (AID) has a negative and significant impact on tax buoyancy at all levels, indicating a major variable. Economic theory (tax handle) predicts a negative impact, which is in line with the results. The findings in this study suggest that high levels of external aid growth in COMESA have influenced the tax performance of developing nations negatively. The reason may come because an increase in foreign resources makes governments in the developing nations relaxed and due to fear of any political unpopularity the governments rely less on domestic resource mobilization. The results are in line with those of Quazi (1994), who found also that it was a major variable significant at all levels with the appropriate sign.

Fiscal deficit (DF) variable is significant at 5% with a negative coefficient of -.0165895 and a p-value of 0.011. The sign is not the expected, and this shows that as the deficit grows big it demotivates the respective authorities from improving their taxing strategies to raise revenue from taxes. The time trend coefficient (Trend) is significant at 5% with a negative sign. Implication is that tax performance is changing over time due to the presence of shocks. The variable explains the presence of time effects and hence economic shocks during the period under study. The possible reasons for such results can be explained by the presence of droughts, civil wars and political instability during the period.

Total expenditure (EXP) is significant at 5% significant level and reports a correct positive sign. This is in line with economic theory. The results for this variable are in line with what Teera (2000) obtained.  The results indicate that as the total spending increases, this causes the tax system to be more buoyant, this is due to an extra effort to collect more revenue through taxation to finance the increasing spending.

Trade openness (XM) variable is not significant but has the correct sign, it has a probability value of 0.210. A positive sign was also obtained by Teera (2000) but significant at 5 % and 10% for low income group and SSA countries respectively. The possible reasons for such results include the undervaluation of imported goods which applies to most own-funds imports (Fjelstad, 1995). This is due to the fact that the importer has access to foreign exchange without going through central bank records. Administrative constraints and corruption at entry points increase the problem of undervaluation of imported goods (Basu and Morrissey, 1993: 22)

The overall model reported Adjusted R-squared of 0.3725. This tells us that approximately 37.25% variation in the annual tax buoyancy is explained by the explanatory variables included in the model. The obtained Adjusted R-squared by Begum (2007) reports a value 0.51 for total tax buoyancy regression and 0.46 for indirect tax buoyancy regression using pooled OLS, no justification was given for such results. It automatically reports to us that there are some variables that explain buoyancy that have been omitted. Some variables have been omitted such as the shadow variable (tax evasion) due to the problem of measuring it.

Conclusion and Policy Recommendation


This chapter contains a detailed conclusion to the study and also some policy lessons drawn from the empirical results of the previous chapter. In addition, the chapter also gives possible areas of future research.


The study has attempted to examine empirically the determinants of tax buoyancy in the developing nations using COMESA countries information for the period 2000-2009. The motivation of the study sort to address the neglected quality dimension of tax performance leading to biased policies, low tax revenue collection against potential revenue that can be raised from national income, deterioration and shortage of public goods, continuous changes in tax rates that are also high as compared to developed nations leading to the rapid expansion of the hidden economy, persistent fiscal deficits and high growing rates of money supply.

Using a panel data, pooled OLS methodology we found out that monetization negatively affects tax buoyancy. This result suggests that monetization seem not to increase tax performance, instead it retards buoyancy levels. Possible reasons of this result may be due to the inability to utilize the growth of money supply to increase the documentation of the economies to increase the collection of each tax. The abuse of the printing of discretionary paper money to finance government activities in developing nations is a possible reason for such results. This reduces effort to raise adequate revenue from collecting taxes. Poor tax administration and also underdeveloped infrastructure may be possible reasons.

Apart from monetization, the study found that growth of agricultural sector, growth of industrial sector, external aid growth, fiscal deficit growth and total expenditure growth to be the determinants. The agricultural sector is still contributing positively to revenue generation processes despite the industrialization going on in developing nations. The industrial sector is worth to be noted, it contributes significantly to tax performance. Respective countries can increase their tax buoyancy by actively encouraging growth in the agricultural and industrial sectors; they should not undermine one sector since both have positive impacts. Fiscal deficit growth and external aid growth have indicated a negative impact on tax performance.

Impact (negative) of economic shocks to tax performance has been found in the study. Economic shocks have been shown by the presence of time effects and their significance in the regressions undertaken. The main causes have been severe droughts due to inadequate rainfall, civil wars and political instability.

Policy Recommendation

Since our findings suggest a negative relationship between monetization and tax buoyancy, maybe for COMESA countries to reap benefits from monetization they need to have strong link between fiscal and monetary sectors, improve tax administration through appropriate reforms, invest in the improvement of infrastructure to facilitate the collection of taxes and stable macroeconomic environment. A strong link between fiscal and monetary sectors facilitates the utilization of the growth in money supply to improve tax performance through increased documentation of the economy. Improvement in tax administration will produce efficient taxing systems which discourages tax evasion and the growth of the hidden economy. Most of all there should be central bank independence from political authorities, the government activities should be financed not from discretionary paper money printing rather they should use other noninflationary ways such as tax collection until the potential level of the economy has been reached.

Policies aimed at developing the domestic taxing systems are beneficial. The policies should be aiming at taking special considerations of the findings in the study. Factors aimed at taking appropriate decisions on variables like fiscal deficits and external deficits since they have been found to have a negative impact on tax buoyancy. In some COMESA countries there are a few numbers of financial intermediaries and stock markets are not well developed, an effort to improve their significance will be an appropriate measure to be undertaken.

Development policies should not be biased towards the growth of one sector rather it has to be across all sectors. Both the agricultural sector and the industrial sectors have proved to be of significance in defining the level of tax performance, and hence they have to be treated without disparity.

Developing nations should however consider maintaining their taxing systems or improve them positively over time. The time trend variable have shown us that over time there is negative effect on tax buoyancy, there is actually a decline and this is to be prevented. Policies aimed at avoiding declining tax performance over time should be developed. Economic shocks like drought should be avoided through forecasting and mitigation strategies developed.


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