Form 16 is needed for the purpose of filing returns, as it will help you file your salary income.
Form 16 is very necessary as it acts as salary proof and tax paid to the government. At the end of the every financial year, the employer provides you form 16.
The Form 16 provides complete details of the salary details of the employee along with necessary adjustments for income tax. Form 16 is applicable for only salaried people.
In case, if you have worked in two different organization in a single year than you have to obtain two diffferent Form 16s from the two companies in order to file the IT returns.
However, it is not compulsory to give the form 16 to the employee if there is no TDS deducted.
This form is for non salaried employee who work as a professional for an organization. This is used in various cases where tax is deducted.
Say for example, interest earned on bank fixed deposits, will results in tax being deduced at source, subject to the interest income being over Rs 10,000. In such cases each financial bank issues TDS certificate to the customers.
Form 16A is issued in cases like interest on securities, winning lottery or horse race, fees earned from professional or technical services etc.