As per the Companies Act and related regulations, the

Solution

As per the Rule 17 of the Companies (Share Capital and Debenture) Rules, 2014, The letter of offer for buyback shall be dispatched to the shareholders or security holders immediately after filing the same with the Registrar of Companies but not later than twenty days from its filing with the Registrar of Companies.   The offer for buy-back shall remain open for a period of not less than fifteen days
and not exceeding thirty days from the date of dispatch of the letter of offer.