Hi Payal,

There are two ways to become an income tax officer.

The best method is to appear UPSC Civil Service exam and choose Indian Revenue Service. Then, you will be posted as Group A officer in Income Tax department. 

The other route is to appear SSC CGL examination. Here, you'll be posted as Inspector. Inspectors work under IRS officers and conduct the raid and all.

Both SSC and UPSC conducts examination every year for the recruitment of candidates to the IT department.

Hope it helps.

All the  best!