You can view your original application using the unique reference number (remember to make a note of this when you submit the original application), make any necessary changes, and then submit it again. This amended application will keep the reference number of the original, although with a new date and time, and will overwrite your original application data. If the corrections are significant and the 4 month time period is advanced then the Member State of Refund can set a new receipt date if they feel it is justified. This will start the 4 month clock again. Guidance will be issued to establish what is considered as a significant change.