income tax vs taxing

income tax

noun

  • A tax levied on earned and unearned income, net of allowed deductions. 

taxing

noun

  • The act of imposing a tax. 

adj

  • Burdensome, difficult. 

  • With respect to an experience: exhausting; draining. 

How often have the words income tax and taxing occurred in a corpus of books? (source: Google Ngram Viewer )