Ash-Shaykh Bin Baaz rahimahullah was asked the following question:

Question:

What is your advice for the unemployed Muslim brothers and sisters who live in England and receive financial support from the government? They sometimes get a job but they do not tell the government about it? Is this deed acceptable?

Answer:

“…There is no harm if they take financial support from the government if it does not lead to abandoning something Wajib (obligatory) or committing something prohibited. However, they may not take this support except in a lawful manner decided by the State; and they should not lie to receive it… ”

[Reference]

A Side Note: It is permissible for him not to inform them concerning earnings which are likely disregarded and not considered in the view of the public mass and Allah knows best.

Mentioned by

AbdulFattaah Bin Uthman
Abu Fajr