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International Research Journal of Finance and Economics
ISSN 1450-2887 Issue 98 September, 2012
© EuroJournals Publishing, Inc. 2012
http://www. internationalresearchjournaloffinanceandeconomics.com
Size and other Determinants of Corporate Effective
Tax Rates in US Listed Companies
Francisco J. Delgado
Corresponding Author, University of Oviedo, Spain
E-mail: fdelgado@uniovi.es
Tel: +34-985104876; Fax: +34-985104871
Elena Fernandez-Rodriguez
University of Oviedo, Spain
Antonio Martinez-Arias
University of Oviedo, Spain
Abstract
This note studies the determinants of corporate Effective Tax Rates (ETR) based on
a panel of listed US companies over the period 1992-2009 (Compustat), with a special
focus on firm size. We also consider the economic and financial structure of the firms, as
well as profitability. The results indicate a non-linear relation between size and ETR, with
similar relationships also found for debt and capital intensity. This may explain the
conflicting results found in the previous literature.
Keywords: Effective Tax Rate, Corporate Tax Burden, US listed companies, firm size
JEL Classification Codes: H25, H32
1. Introduction
Most business decisions have tax implications and taxation may have significant implications for
corporate decisions, so companies should take the tax burden into account when designing their
strategies. It is therefore important to know the main determinants of the Effective Tax Rate (ETR)
borne by companies.
The corporate tax burden has been the subject of several empirical studies1 and this one focuses
on US companies. 2 For an accurate analysis of the corporate tax burden, it is best to use the ETR
because the Statutory Tax Rate (STR) is not a good indicator as it does not take into account temporary
differences, tax credits and other fiscal incentives (Government Accountability Office, 2008, p. 1).
Most research on the ETR has been aimed at identifying its determinants. However, as we show
in Section III when we perform a comparative analysis of our results, previous studies have found
conflicting results for the determinants of ETR, and in particular firm size, for both time intervals and
different samples.
1 Recently Hanlon and Heitzmanl (2010) and Graham et al. (2012) have published excellent reviews on these topics.
2 Other studies outside the US can be consulted in Fernández-Rodríguez and Martínez-Arias (2011).
International Research Journal of Finance and Economics - Issue 98 (2012) 161
This research focuses on the effect of size and other determinants on the corporate tax burden.
With this aim we analyze size both separately as well as combined with other variables which
influence taxation, such as leverage, capital and inventory intensities and the profitability. The paper
contributes to the literature on ETRs because it adopts a non-linear approach, as opposed to the linear
approach often used in previous research, and it also covers an extensive and recent period (1992-
2009). The paper is structured as follows: Section 2 presents the methodology and data, Section 3
shows the main findings and Section 4 concludes.
2. Model and Data
The definitions used in the literature for ETR vary, though almost all studies use the ratio of current
income tax expense and pretax income. 3 This is the main option used in this paper. However, in
Section III we include a sensitivity analysis with an alternative measure for ETR, the ratio of total
corporate income tax expense to pretax income.
In order to identify the determinants of ETRs, the following panel data model is used in its full
version:
it
SECTORYEAR
it
ROA
it
INVINT
it
CAPINT
it
CAPINT
it
LEV
it
LEV
it
SIZE
it
SIZE
it
ETR
10987
2
65
2
43
2
210 (1)
The model contains the explanatory variables that are traditionally used in this type of study:
Size (SIZE): the logarithm of the firm’s total assets.
Leverage (LEV): the ratio of total debt to total assets.
Capital Intensity (CAPINT): the ratio of property, plant and equipment to total assets.
Inventory Intensity (INVINT): the ratio of inventories to total assets.
Return On Assets (ROA): the ratio of earnings before income tax over total assets.
In order to capture any possible non-linearities, the squares of the most relevant variables are
also added. In addition, dummies have been included to account for the time effect (YEAR) and the
sectoral effect (SECTOR).
The data for this research was obtained from the Compustat data base, which provides
information on the financial statements of non-financial, US-listed companies for the period 1992-
2009. The sample consists of 2,500 companies for each year, although some do not give information
for the whole period. Moreover, the companies have been classified by sector, following the Standard
Industrial Classification (SIC).
Fig. 1 shows the trend in annual ETR over the period studied. Note that the corporate tax
burden dropped from 1992 to 2004 but in 2005 there was a marked rise to a level of about 25%, where
it has remained over recent years at about 25%. The highest ETR is for the first year (28.42%) and the
lowest for 2004 (21.32%), a difference of seven points. However, the variation between the first and
the last year is less than three percentage points, which points to a fair degree of stability throughout
this long time series. The results also show a large gap between the ETR and the STR, which remained
at about 40% over the whole period. Table 1 shows the descriptive statistics for the variables used in
the model (1a) and the correlation matrix (1b).
3 See the surveys by Callihan (1994) and Plesko (2003).
162 International Research Journal of Finance and Economics - Issue 98 (2012)
Figure 1: Annual versus mean corporate effective tax rates (1992-2009)
Source: Compustat and own elaboration
Table 1: Descriptive Statistics and correlation matrix
A) Descriptive statistics
ETR SIZE LEV CAPINT INVINT ROA
Mean 0.2542 5,9927 0.3989 0.2817 0.1222 0.0113
Median 0.2836 5,9819 0.3942 0.2137 0.0831 0.0630
Standard deviation 0.1883 2,0957 0.2040 0.2324 0.1344 0.2357
Minimum 0.0000 -6,9078 0.0000 0.0000 0.0000 -1.6740
Maximum 1.0000 13,5896 1.0000 1.0000 0.9206 0.4137
N.Observations 25,751 37,498 36,271 34,525 33,326 33,830
B) Correlation matrix
VARIABLE ETR SIZE LEV CAPINT INVINT ROA
ETR
SIZE 0.315***
LEV 0.049*** 0.222***
CAPINT -0.008 0.235*** 0.187***
INVINT 0.221*** -0.063*** 0.125*** -0.157***
ROA 0.461*** 0.349*** -0.016*** 0.120*** 0.157***
***, **, * denotes statistical significance at the 1%, 5% and 10% levels, respectively.
Source: Compustat and own elaboration
3. Empirical Results
The main results, which come from the fixed effect model, are shown in Table 2. 4 In order to study the
SIZE-ETR relation (1) in greater depth, the model was estimated including other variables such as
leverage (2), capital intensity (3), inventory intensity (4) and Return On Assets (5). Finally, the full
4 The F-test and the Pagan Lagrange Multiplier test were performed and indicated the presence of individual effects and the
advisability of using panel data rather than the pooled model. The Hausman test was then applied. It advised the fixed
effects model rather than the random effects model.
International Research Journal of Finance and Economics - Issue 98 (2012) 163
model was estimated including all the variables mentioned (6). This gives a good fit in comparison
with previous research.
The entity size variable was significant in all the models estimated, showing non-linear
behavior characterized by a positive coefficient for values which are low in size and a negative one for
high size levels. The former is consistent with the government control hypothesis which predicts higher
ETRs for larger companies because of tighter control of their results and taxes. The second supports
the hypothesis of greater fiscal planning on the part of larger companies with a view to reducing their
tax burden. Since this is a sample of large companies, as they are all listed on the Stock Exchange, the
results therefore show that the effect of fiscal planning is greater than government control after a
certain size.
Size is the variable that has been most extensively studied in previous research on corporate
taxation, either alone or in combination with other variables, with varying results. Some studies found
a positive relation between size and ETR (Zimmerman, 1983; Wang, 1991; Omer et al., 1993; Plesko,
2003), but others found the opposite (Porcano, 1986; Chen et al., 2010). There were even studies that
found no significant relation between the two variables (Stickney and McGee, 1982). The diversity of
these results is perhaps explained by the presence of this non-linear relation between size and ETR,
which is maintained in all our estimates.
Moreover, there were other interesting non-linear relations with the ETR, namely those relating
to debt and capital intensity. Although in research on debt there is usually an inverse relation with ETR
(Stickney and McGee, 1982; Plesko, 2003), in some papers the opposite was found (Chen et al., 2010).
When debt is very low the deductibility of interest is probably not sufficient to lead to a drop in tax
burden. However, with high levels of debt, very high interest deductibility is able to reduce company
tax pressure.
Regarding capital intensity, the most widely-obtained result is an inverse relation with ETR
(Stickney and McGee, 1982; Gupta and Newberry, 1997), although once again not all studies have
reached the same conclusion (Plesko, 2003). Again, the change in sign in CAPINT-ETR indicates that
when levels of property, plant and equipment are low, companies are unable to reduce their tax burden.
On the other hand, after a certain level of capital intensity, companies note a reduction in ETR caused
by the deductibility of high depreciation.
Whit respect to inventory intensity, a variable that has been little used in the literature, the
results show a positive relation with ETR, as in Gupta and Newberry (1997). That is, companies that
have higher levels of stocks are subject to greater tax pressure. Finally, as in all prior research
(Stickney and McGee, 1982; Wilkie and Limberg, 1993; Gupta and Newberry, 1997; Plesko, 2003;
Chen et al., 2010), business profitability has a positive effect on tax burden.
Moreover, we have conducted a sensitivity analysis with an alternative measure of ETR,
arriving at similar conclusions (Table 3). As stated above, the new definition of ETR is the ratio of
total corporate income tax expense and pretax income, so it takes into account the deferred tax.
Table 2: Determinants of corporate effective tax rates (main measure)
Expected sign Models
(1) (2) (3) (4) (5) (6)
SIZE +/- 0.0410***
(17.01) 0.0518***
(17.57) 0.0414***
(17.13) 0.0421**
(17.21) 0.0534***
(16.11) 0.0594***
(16.34)
SIZE2 +/- -0.0012***
(-4.93) -0.0021***
(-7.58) -0.0012***
(-5.05) -0.0012***
(-4.78) -0.0022***
(-7.53) -0.0027***
(-8.27)
LEV +/- 0.1107***
(4.94) 0.1230***
(5.08)
LEV2 +/- -0.1356***
(-5.61) -0.1503***
(-5.87)
CAPINT +/- 0.0552***
(2.18) 0.0837***
(2.96)
CAPINT2 +/- -0.0775**
(-2.58) -0.1267***
(-3.85)
INVINT + 0.0937***
(5.24) 0.0982***
(4.97)
164 International Research Journal of Finance and Economics - Issue 98 (2012)
Table 2: Determinants of corporate effective tax rates (main measure) - continued
ROA + 0.0449***
(7.12) 0.0488***
(6.99)
Year Dummy Yes Yes Yes Yes Yes Yes
Sector Dummy Yes Yes Yes Yes Yes Yes
Adjusted R2 0.1876 0.2019 0.2015 0.2405 0.2583 0.3431
Nº observations 25,733 25,025 25,684 24,857 25,151 23,753
***, **, * denotes statistical significance at the 1%, 5% and 10% levels, respectively.
Table 3: Determinants of corporate effective tax rates (alternative measure)
Expected sign Models
(1) (2) (3) (4) (5) (6)
SIZE +/- 0.0453***
(25.30) 0.0572***
(26.61) 0.0452***
(28.18) 0.0460***
(25.19) 0.0538***
(22.40) 0.0581***
(22.21)
SIZE2 +/- -0.0014***
(-8.23) -0.0024***
(-12.32) -0.0014***
(-8.10) -0.0015***
(-8.30) -0.0022***
(-10.56) -0.0026***
(-11.45)
LEV +/- 0.1030***
(6.37) 0.1193***
(6.80)
LEV2 +/- -0.1362***
(-7.80) -0.1438***
(-7.76)
CAPINT +/- 0.0270
(1.46) 0.0484**
(2.38)
CAPINT2 +/- -0.0189
(-0.87) -0.0524**
(-2.23)
INVINT + 0.0537***
(4.08) 0.0530***
(3.72)
ROA + 0.0779***
(16.50) 0.0834***
(16.10)
Year Dummy Yes Yes Yes Yes Yes Yes
Sector Dummy Yes Yes Yes Yes Yes Yes
Adjusted R2 0.2919 0.2998 0.2914 0.3221 0.4242 0.4544
Nº observations 28,228 27,484 28,181 27,182 27,614 26,014
***, **, * denotes statistical significance at the 1%, 5% and 10% levels, respectively.
4. Concluding Remarks
This paper analyses the determinants of company taxation in US listed companies based on a panel for
the period 1992-2009 taken from Compustat, paying special attention to size. We consider the ETR as
the ratio of current income tax expense to pretax income; however, in order to achieve more robust
results, the estimations are also performed with an alternative measure.
Our results indicate a non-linear relation between size and ETR, with smaller companies being
subject to a greater tax burden. After a certain size, the effect of tax planning exceeds that of
government control so companies are able to reduce their ETRs. Two other very interesting non-linear
relations with ETR were obtained for debt and capital intensity, indicating that companies can only
reduce their tax pressure after certain levels of debt and capital intensity have been reached.
The conclusions drawn in this study are relevant because previous research had always
indicated linear relations between these variables and ETR, which might explain the contradictory
results in the literature.
References
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than non-family firms?”, Journal of Financial Economics, 95, pp. 41-61.
[3] Fernández-Rodríguez, E. and Martínez-Arias, A., 2011. “Determinants of effective tax rate:
evidence for USA and the EU”, Intertax, 39, pp. 381-395.
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