The Islamic State of Iraq and Greater Syria (ISIS) is making revenues to the tune of $80 million a month. ISIS is able to generate more revenues by taxing the areas it controls, oil production and selling it. ISIS has developed six funding channels to sustain and expand its activity.

The oil income accounts for over 40 percent of total revenues to the ISIS. 

The monthly revenue of $80 million makes a yearly income that's equivalent to the 2014 GDP of Samoa, an independent nation with a population of 198,000 in South Pacific. The US-led coalition's strikes reduced ISIS' capability to generate revenues from oil production to some extent. 

According to a report by IHS, the Islamic State of Iraq and Greater Syria doesn't depend upon donations but prefers to create its own revenue source. In addition to oil production and selling it, ISIS is believed to have involved in selling drugs and antiquities and kidnapping for ransom, as published by Time.

ISIS has been able to establish a quasi-state administration in some parts of the Middle East region. ISIS had recently claimed the responsibility for attacks in Paris. The terrorist attacks in November killed 130 people.  

In a report by the Financial Times, Columb Strack, senior analyst at IHS, described ISIS as unlike al-Qaeda in the sense that the Islamic State has not been dependent on money from foreign donors to avoid leaving it vulnerable to their influence.

The six funding channels of ISIS include the production and smuggling of oil and gas, taxation on people in the areas it controls, confiscation of land and properties, trafficking of drugs and antiquities, criminal activities such as bank robbery and kidnap for ransom and state-run business.

Several western nations are fighting against ISIS. The US, Britain and other countries have combined together to launch air strikes in Syria to destroy ISIS's revenues sources. The main objective of western forces is to stop the revenue source of oil production for ISIS. 

According to a report by Business Insider, oil revenues for ISIS are estimated to be $50 million every month making $600 million per annum. The government insists that bombing oil trucks and fields is the best way to destroy ISIS revenue sources.

However, campaigners and some politicians are questioning the government's decision on this.

ISIS is getting revenues up to 43 percent from oil production and smuggling. Financial Times' investigation in October revealed that ISIS' oil revenue was $1.5 million per day while IHS estimated $1.1 million per day.