Excise duty guarantee certificates with specific due date which are issued until 12th of January, 2018, are valid with conditions specified therein until the end of due date or until the first re-registration. Whereas, excise duty guarantee certificates with unspecified due date which are issued until 12th of January, 2018, are valid with conditions specified therein until 31st of December, 2018, or until the first re-registration.