Voucher Start and End dates

It would be great to be able to add a Start date and bring back the End date (which used to be possible but has been changed to "valid for a certain time").  Reason behind this would be to have more flexibility when we do our promos.  For instance, receive a voucher valid from and to a specific date (like the promos we often see that makes a voucher valid from January to February only).  Right now that's not possible as the expiration date of the voucher has to be based out of the date of purchase, which is not always the case.