Working for an insurance company

Firstly: 

Life
insurance is a kind of commercial insurance, which is haraam, because it
involves uncertainty, riba and gambling, and consuming wealth unlawfully. It
is not permissible to work in commercial insurance companies, because this
is a kind of cooperating in sin, which Allaah has forbidden, as He 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. And fear Allaah. Verily,
Allaah is Severe in punishment”

[al-Maa’idah 5:2] 

See also
question no. 8889. 

Secondly: 

There is
nothing wrong with your keeping the money that you earned from working in
that company before you came to know that it is haraam, because Allaah says
(interpretation of the meaning): 

“So
whosoever receives an admonition from his Lord
and stops eating Ribaa, shall not be punished for the past; his case is for
Allaah (to judge)”

[al-Baqarah 2:275] 

With regard to the money
that you took from the company after you came to know that it is haraam,
then you have to get rid of it, because it is haraam wealth, so you can
spend it on charitable causes. 

See also
questions no.
33852 and 2492. 

See
Fataawa al-Lajnah al-Daa’imah li’l-Buhooth al-‘Ilmiyyah wa’l-Ifta’, 15/8. 

And Allaah knows best.