https://www.epo.org/en/node/what-happens-if-i

What happens if I wrongly pay a reduced amount?

If the EPO notices an underpayment due to incorrect application of the reductions, the solution will depend on whether the payment can be corrected before the final due date, and whether the underpayment is linked to the cap of 5 applications in 5 years.

If the underpayment is because your application does not meet the cap requirement, the EPO will invite you to pay the missing amount within two months.

In other cases (for example, if you claim a reduction when you do not qualify as a micro-entity), your application may be considered to be withdrawn unless the error is detected and corrected before the payment is due.

Even if an application is deemed withdrawn in such cases, you are still able to make use of the legal remedies available depending on the specific circumstances of the case, such as further processing or re-establishment of rights.

In more detail:

A non-justified payment of a reduced fee is treated as an underpayment, with the legal consequence that the fee payment is considered not to be effective, i.e. not validly made from a legal point of view.

If you

  • (a) missed the deadline for the payment or
  • (b) requested a reduction, but the verification showed that it was not justified,

the usual legal consequence is that your application will be deemed withdrawn (unless otherwise stated, e.g., in the case of renewal fees for European applications).

To remedy this situation, you may request further processing under Article 121 and Rule 135 EPC, if available, or re-establishment of rights under Article 122 EPC. The EPO will inform you about the options available.

If you claim a micro-entity fee reduction, the EPO will check whether you have exceeded the cap. If you pay a reduced fee under Rule 7a(3) EPC but have already reached the cap, the EPO will invite you to correct the payment within two months from the invitation, and your application will not be deemed withdrawn if you pay the missing amount within this period. Note that the two-month period only applies for the cap.

If you pay only a reduced fee without having claimed a reduction for the application, the EPO will treat this as a normal underpayment. Please remember that you must make the declaration of the status as a micro-entity or small entity at the latest when paying the reduced fee.

The EPO may ask you to provide evidence to support your declaration or, in rare cases, to clarify whether previous applications also belong to you.