I hope this helps you understand the solution to your problem. Please note that the tax liability will also be calculated by deducting the HRA to the eligible limit and the medical bills depending on a case-to-case basis. Again, if the person fails to invest under Section 80C (with a cap limit of 1 lakh), the deducted 1 lakh should not be deducted, and the whole income is to be taxed. Also, if the person has a small income from other means which he asks your firm to adjust, the same is to be adjusted. I believe this will depend on the company policy. Hope this helped.