1.1 Agency Theory 
In agency theory, the parties involved are the 
management of a company, acting as agents, and the 
investors, acting as principals. The agent and the 
principals have different interests, and the principal 
relies on the agent to protect those interests (Godfrey 
et al., 2010). Jensen and Meckling (1976) stated that 
the separation between the owners and managers of 
a company may cause agency problems or conflicts. 
Because the agent and the principal have different 
interests, the principal have to spend on the costs of 
agency, including: (1) the monitoring expenses 
incurred by the principal to supervise the behavior of 
agents, (2) the bonding expenses incurred by the 
agent to ensure that the agent will not act in a way 
that harms the principals interests, and (3) the 
residual loss in the form of decreased levels of well-
being, for both parties. 
1.2  Tax Planning and Firm Value 
According to Pohan (2013) tax planning is the 
process of organizing personal and corporate 
taxpayer businesses by utilizing loopholes that can 
be taken by companies in the corridor of the 
provisions of taxation regulations. Thus, the 
company can pay taxes in the minimum amount. 
According to Zemzem and Ftouhi (2016), Oyeyemi 
and Babatunde (2016), Zemzem and Ftouhi (2013), 
Fajrin et al., (2018) stated that tax planning 
negatively affect firm value. This shows that the 
smaller the payment of corporate taxes the higher 
the value of the firm. If a company is able to reduce 
tax payments it will make the profits generated by 
the company greater so investors will be interested 
in buying company shares.
 Based on the explanation 
above, the hypothesis built is: 
 
H
1
: Tax planning negatively affects firm value 
1.3  Institutional Ownership and Firm 
Value 
Institutional ownership is the ownership of company 
shares by institutions (pension funds, investment 
companies, banks and others). According to Parrino 
et al., (2003), Ferreira and Matos (2008), Alfaraih et 
al., (2012), Fazlzadeh et al.,  (2011) and Uwuigbe 
dan Olusanmi (2012), institutional ownership 
positively affects firm value. The greater the 
institutional ownership, the higher the value of the 
company will be. According to Chung et al., (2002), 
institutional ownership has an important role in 
monitoring management so as not to take 
opportunistic actions for personal interests so the 
value of the company will increase. Based on the 
explanation above, the hypothesis built is: 
 
H
2: 
Institutional ownership positively affects firm 
value 
1.4  Board of Director and Firm Value 
In this study the board of directors is a supervisor in 
the company or also called the board of 
commissioners, where the board of commissioners is 
an organ in corporate governance that oversees 
management in managing the company. According 
to Andres and Vallelado (2008), the board of 
directors has a positive effect on firm value. This 
shows that the more the number of board of directors 
in the company the higher the value of the company 
because it will improve supervision, governance, 
and increase returns (Andres and Vallelado 2008). 
Based on the explanation above, the hypothesis built 
is: 
 
H
3: 
Board of director positively affects firm value 
1.5  Independent Board and Firm Value 
The independent board is a member of the Board of 
Commissioners who has no relationship with the 
company. According to Trisnantari (2010) and 
Amyulianthy (2012), the independent board has a 
positive effect on firm value. This shows that the 
greater the number of independent boards, the higher 
the value of the company, because the independent 
board is able to carry out the monitoring function to 
oversee the policies and activities carried out by the 
directors. The existence of an independent board in 
the company can provide an effective contribution in 
the process of preparing more high quality financial 
statements (Muryati and Suardika 2014). Based on 
the explanation above, the hypothesis built is: 
 
H
4: 
Independent board positively affects firm value 
1.6  Corporate Governance Moderates 
the Relationship between Tax 
Planning and Firm Value 
In this study, we also wanted to test whether 
corporate governance moderates the influence of tax 
planning with firm value. Based on the results of 
Zemzem and Ftouhi (2013), Nike et al., (2014), 
Wahab and Holland (2012) and Winanto and Utoyo 
(2013), corporate governance is able to strengthen 
the negative influence of tax planning on firm value. 
This is because companies that have good