Form 15G and Form 15H are documents you can submit to make sure TDS is not deducted from your income if you meet the conditions mentioned below. Also, you must have a PAN before applying for these forms. Some banks allow these forms to be submitted online through the bank’s website. DSC is required to submit the form online.

Form 15H is for senior citizens; those who are 60 years or older, while Form 15G is for everybody else.

Form 15G and Form 15H are valid for one financial year. So you have to submit these forms every year if you are eligible. Submitting them as soon as the financial year starts will ensure the banks don't deduct any TDS on your interest income.

For more information, read this article on Form 15G and Form 15H.