Answer
(Fatwa: 668/622=D/1429)
It is allowed to write accounts of lawful transactions of your company and to analyze and check the accounts. Your income while working in your company and maintaining accounts of the abovementioned companies is lawful, but accounting and analyzing of accounts of banks and insurance companies is not allowed. It is unlawful for you to work for banks and insurance companies during the employment; therefore you must shun from it. However, the salary will not be haram if you have to do the job partly.
Allah (Subhana Wa Ta’ala) knows Best
Darul Ifta,
Darul Uloom Deoband