Praise be to Allaah.
Firstly:
We have quoted on several previous occasions the evidence to
prove that it is not permissible for a Muslim to settle in any kaafir
country except in cases of need or necessity, subject to certain
conditions.
See questions no. 3225
and 13363.
Secondly:
If a Muslim enters such a country, he must adhere to the
conditions that have been stipulated. Allaah says (interpretation of the
meaning):
“O you who believe! Fulfil (your) obligations”
[al-Maa'idah 5:1]
It is not permissible for
a Muslim to betray them or cheat them. The Prophet (peace and blessings
of Allaah be upon him) said: “Render back trusts to the one who entrusted
you, and do not betray the one who betrays you.” Narrated by Abu Dawood,
3534; classed as saheeh by al-Albaani in Saheeh Abi Dawood.
And the Prophet
(peace and blessings of Allaah be upon him) described one of the attributes
of the hypocrite as being: “When he enters into a covenant, he proves
treacherous.” Narrated by al-Bukhaari, 34; Muslim, 58.
The Prophet (peace and blessings of Allaah be upon him)
used to send his companions to fight the mushrikeen, and one of the things
he advised them was: “Do not be treacherous.” Narrated by Muslim, 1731.
This is something which demonstrates the greatness of Islam
and the perfection of its laws, for it forbids its followers to be
treacherous or to cheat even its enemies.
This state has allowed you to stay there, subject to certain
conditions, so you are obliged to fulfil them.
Based on this, it is not permissible for you to conceal your
work from them so that you can avoid paying taxes and take the monthly
allowance when it is not permissible for you.
And Allaah knows best.
See also question no.
5218 and 14367.
And Allaah knows best.