Form-16 is one of the most crucial document required to file an ITR, since it gives a detailed breakdown of all your salary components, the deductions claimed by you, and the total tax deducted by the your employer, or employers during the financial year.
If you have changed jobs during the financial year, be sure to collect Form-16 from both your employers. Note that it is not mandatory to have this document while filing ITR. It has 2 parts, where part A details the TDS deducted on your salary, while part-2 provides details of your income, deductions claimed.

