Income Tax refund arises in case of a mismatch between the tax amount paid and the actual payable amount. If the amount paid is higher than the actual amount payable, a refund is initiated. The Form 30 is used for the same purpose.
Under the income tax and other Direct tax laws, tax refunds arise in those cases where the amount of tax paid by a person (or paid on his/her behalf) is greater than the amount on which he/she is properly chargeable. This is noted under Sections 237 to 245 of the Income Tax Act, 1961.
There are many cases wherein you will be eligible for a refund. Some of them are: