Every citizen is legally bound to pay tax to the government to enable to meet its expenditures to discharge its obligations regarding defense, education, public health, law and justice, infrastructure etc. In most of the countries, tax revenue is a major source of government income. Taxes also play a very important role in the economic development of a country. Tax evasion is concerned with all unlawful activities which are adopted by the taxpayers in order to escape from the payment of tax. The objective of this study is to probe the determinants (causes) of tax evasion in Pakistan from both tax payers and tax collectors point of view. In order to record the views of both tax payers and tax collectors the author has collected data from 150 respondents through two separate structured questionnaires. The data collected through this method has been analyzed through different statistical techniques such as arithmetic mean, percentages, standard deviation, t-tests, ANOVA etc. The results highlight six main cause of tax collection: unproductive expenditures / misuse of funds, anti-tax culture, corrupt tax administration, multiple & higher tax rates, complex tax system and amnesties and incentives for tax evaders. The author has also made certain recommendations to combat tax evasion problem and submitted suggestions to improve tax collection in order to ensure financial independence of Pakistan.