It is mandatory to file return of income for a company and a firm. However, individuals, HUF, AOP, BOI are mandatorily required to file return of income if the income exceed basis exemption limit of Rs 2.5 lakhs. This limit is different for senior citizens and super senior citizens.

According to the Income Tax Department, Your total income, could be Salary from house property, profit or loss from selling stocks or from interest on a savings account or fixed deposits. All these numbers get added up to become your gross income.

• Income from Salary: All the money you receive while rendering your job as a result of an employee empoyement contract.
• Income from House Property: Income from house property you own; property can be self-occupied or rented out.
• Income from other sources: Income accrued from Fixed Deposits and Savings Account come under this head.
• Income from Capital Gains: Income earned from sale of a capital asset, say mutual funds or house property.
• Income from business and profession: Income/loss arising as a result of carrying on a business or profession. Freelancers income come under this head.

TDS on salary means that tax deducted by the employer at the time of transferring the salary into the employee's account. The amount deducted from the employee's account is deposited with the government by the employer.

Form 16 is the certificate issued under section 203 of the Income-tax Act for tax deducted at source (TDS) from income under the head 'salary'. It is issued on deduction of tax by the employer from an employee's salary and deposit of the same with the government. The form has two parts: Part A and Part B

Form 26AS is an annual consolidated credit statement issued under Section 203AA of the Income-tax Act, 1961. It contains details of various taxes deducted on your income by deductors: be it ca be your employer, bank, or even a tenant.