LTA cash voucher deduction for private employess

Hi 

I am working in private IT firm. I have not opted for LTA as a flexi salary component. I am in discussion with my employer to add this in my salary structure. I guess it can be done

I recently purchased two term insurance policies from ICICI PRUD & HDFC Life. The yearly premium which I paid is approximately 165000/-. Now I want to take this amount for my LTA cash voucher deduction. According to my calculation deduction I could get is 55220/-. 

I am not sure how can claim this deduction. Since in our organization. investment declaration & proof submission process is already over. Now I am not sure I can claim this deduction though I am checking with employer

My point is if my employer did not allow this deduction then can I claim it separately while filling ITR ?

Since LTA is not opted as of now & suppose employer do not allow to add it further then still can I claim it in ITR ?