Commission ??

What is the nature of this commission? If this income is non-recurring and uncertain and cannot be anticipated, then it can be called casual income, and it can be charged under the head income from other sources, in which case you can use ITR 1.

This is such type of commission which is paid on each case which is finalised by sanctioning of loan.

So this is definitely directly related with the no. and amount of loan he will going to sanction.

Yes, definitely it cannot be anticipated as same as a doctor who can't know how many client he will going to treat in a upcoming year. 

Commission received will be chargeable to tax under the head income from salary since it is also the same company. You can file ITR-1.