• For a government to finance itself, it must usually collect taxes. Tax policy is often a contentious topic, with proponents from different schools of political thought disagreeing over who should pay taxes at what level. However, there are a number of principles of taxation that most parties can agree on, even if their ideas about how to carry them out can differ greatly.
  
  

Transparency

• One of the most important principles of tax law should be be that it is transparent. That means that taxpayers know the rules of taxation, both for their own taxes and for others. This can allow taxpayers to know how much they are required to pay for the government in advance, to allow for proper financial planning, and to ensure that the government's process of taxation is not seen as arbitrary.
  
  

Fairness

• Tax laws should require that everyone pay her fair share of taxes. This means that certain groups should not be allowed to pay less than is fair due to a privileged status. However, while nearly all parties can agree upon fairness as a principle, definitions of a "fair" tax policy can differ radically. For example, while some believe it most fair for everyone to pay the same rate of income tax, others believe it for fair for those who earn more to pay a higher rate.
  
  

Enforceability

• In order for a system of taxation to work, it must be enforceable. A government can assess as many taxes as it wishes, but if it has no means of enforcing their collection, many will likely choose to not contribute. The enforcement mechanism may take the form of a government agency, such as the Internal Revenue Service, with power to assess penalties for failure to pay taxes.
  
  

Effectiveness

• Tax systems must be effective, in the sense that they are able to produce the result that is required of them. For example, if a tax system is applied to raise money to fund government programs, it must be designed to raise enough money so these programs receive sufficient funding. If a tax system is designed to promote certain industries, such as by charging one industry a lower rate of taxes than another, the rates must be set at a level that will produce the desired result.
  
  

Coherence

• Tax laws must always be coherent. This means that the laws do not contradict each other. Tax laws should be written to minimize the amount of vagueness in the language. If disputes or misunderstandings arise, the government should have a means of resolving the confusion, such as through the rulings of a court.