Form 16 is a certificate issued by employer to his employee. It certifies that TDS has been deducted on your salary by the employer. If an employer deducts TDS on salary, he must issue income tax Form 16 as per the income tax rules . Form no 16 is issued once in a year, on or before 31st May of the next year immediately following the financial year in which tax is deducted.
It has two parts, Part A and Part B. Part A has information of the employer & employee, like name & address, PAN and TAN details, period of employment, details of TDS deducted & deposited with the government. Part B includes details of salary paid, other incomes, deductions allowed, tax payable etc.