Minimum subscription requirement triggers unblocking and refund of application money; delayed unblocking attracts interest from the issuer. Minimum subscription requires a prescribed threshold of the base issue size, with an exemption for issuers of tax-free bonds. If minimum subscription is not received, all blocked application money must be unblocked within the specified working day period from issue closure or such time as the Board specifies; failure to do so obliges the issuer to pay interest on the delayed amount at the prescribed annual rate for the delayed period.