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
|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.