An essential condition for a valid payment to the EPO in the case of payment or transfer to a bank account held by the European Patent Organisation is that the amount is entered in that account. The payment is valid in respect of the amount entered. If an insufficient amount has been paid by mistake, it is not possible to rectify the error by having the shortfall paid subsequently deemed to be paid on the original date of payment. Payment is a matter of fact whereby a certain amount is transferred to and put at the disposal of the EPO. It is not, therefore, a procedural declaration which may be corrected pursuant to Rule 139. The same applies to debit orders (see T 170/83, reasons 8). Therefore, time limits for payment are in principle deemed to have been observed only if the full amount of the fee has been paid in due time. However, the EPO may, where this is considered justified, overlook any small amounts lacking without prejudice to the rights of the person making the payment (Art. 8 RFees).