If you buy your flat and stay there,no HRA benefits,obviously as you will not be paying any rent.So even if you receive HRA it will be fully taxable.For principal repayment on your loan you will get a deduction under sec 80C within the overall limit of Rs 1 lac alongwith all eligible investments.For interest,you will get a deduction of upto Rs 1.50 lacs per annum.I assume that you will be staying in your own flat.
