Hi,
There are many factors that we need to consider while calculating income tax (IT) on salary. Usually, IT on salary is calculated and deducted in the form of TDS each month from the salary. This is mandatory for every company. If it is not done, the company will be liable to pay interest as well as penalties.
First of all, please note that IT on salary is not calculated on Cost to Company (CTC). It is always calculated on the net taxable income. I have provided an example of IT calculation in the attached Excel sheet. It is based on some assumptions and will vary if any of the assumptions change. I am also attaching a sheet showing the rates and possible exemptions from tax. In case of any doubt, please email me.