If funds are withdrawn by an SSIA holder before the account matures he has broken the fundamental condition of the scheme. If he could do so without having the 25% top-up clawed back he would have received as large a bonus as someone who left the same amount on deposit for five years, despite having done so himself for only a relatively short time. People who had already withdrawn money from the scheme and paid 23% on the withdrawal might feel aggrieved that others who failed to meet the same condition were treated preferentially.