No need to worry if you have missed the last date of income tax return filing. You still can file your income tax return.
Before that you need to know your income tax for the financial year. If you are a salaried person, check your Form 16. You will come to know how much tax has been deducted by your employer.

There are two scenarios –

No tax to be paid to IT department

It means you don’t have to pay tax to the income tax department. In this case you can file your income tax return before 31st March next year. For example – If you didn’t file tax return on or before July 31st 2010, you can still file your tax return before 31st March 2011.

Tax to be paid to IT department

This may happen because of certain reasons which are as follows –

You changed job in the financial year.

Inadequate information provided to the employer.

Wrong tax calculation

In such cases, you have to owe tax to the IT department. You can still pay tax to the IT department before 31st March with a penalty of 1% per month of delay on the taxes due. For example – If you have to pay a tax of Rs 20,000 on your income and you have not paid by the due date, you will pay a penalty of Rs 200 per month post the due date ( in this case July 31st).

It is always advisable to pay your tax before the due date in order to avoid paying penalty and also losses incurred are not carried forward to next year.