Except as otherwise provided in this subdivision, whenever through inadvertence, mistake or any other means erroneous charges or credits are found to have been made to an employer’s account, the same shall be readjusted as of the date of discovery. Such readjustment shall not affect any computation or rate assigned prior to the date of discovery, but there shall be an immediate recomputation, in accordance with the applicable provisions of this subdivision, of such employer’s account with notice to the employer of the result thereof. If such recomputation results in a contribution rate either higher or lower than that rate in effect on the date of discovery, such new rate shall become effective and applicable to taxable wages as of the first day of the quarter next succeeding the quarter in which the discovery is made.