I have found work in a government department and I know for certain that the income of this department is mostly – more than 90% – composed of mukoos (taxes, levies). Is it permissible for me to work in this department when my salary will inevitably come from their income? What is the general ruling on this issue, I mean the ruling on working on a project for one whose wealth is haraam? Is it different if the owner of this work is the state or one of its representatives, as opposed to a private individual or company?.


Praise be to Allaah.

Firstly: 

We have previously discussed the ruling on mukoos on this
website and we have stated that it is haraam, because Allah, may He be
exalted, says (interpretation of the meaning): “O
you who believe! Eat not up your property among yourselves unjustly”
[an-Nisa’ 4:29]. And the Prophet (blessings and
peace of Allah be upon him) said: “It is not permissible to take the wealth
of a Muslim except with his consent.” Narrated by Ahmad; classed as saheeh
by al-Albaani in al-Irwa’, 1459 

For more information please see the answer to question no.
25758 

Secondly: 

|With regard to your work, if your work involves helping in
something haraam, such as the mukoos (taxes, levies) and so on, then it is
not permissible, because Allah, may He be exalted, says (interpretation of
the meaning): “Help you one another in Al‑Birr and At‑Taqwa (virtue,
righteousness and piety); but do not help one another in sin and
transgression” [al-Maa’idah 5:2].

But if your work does not involve haraam things, and the
Department has other sections that do not deal with haraam things, you can
work in those permissible sections, and whatever salary you take in return
for this permissible work, there is nothing wrong with you taking it. 

For more information please see the answer to question no.
31781

And Allah knows best.