A put option is an option that many bonds offer wherein the investor can sell the bonds back to the issuer at a predetermined price after completion of a basic lock-in period. On exercising put option by an investor, a debit corporate action will be carried by NSDL where the balance under the instrument is reduced to zero. The details of put option exercised by investors will be provided by the company to NSDL. The way it works is that you need to first exercise the put option directly with your bond issuer. Once the put option is verified by the issuer and found to be acceptable in all ways, the next step is to intimate the DP about the same. It is only after this that the DP will pass a debit transaction in your demat account and reduce the balance of holdings to zero. Once that entry is passed, the issuer of the bond is intimated and takes care of the redemption process.