Subsequent to the applicable event mentioned in H‑II, 2.2, the prosecution of further amendments proposed by the applicant is within the discretion of the examining division. Giving the examining division this discretion is intended to ensure that the examination procedure is brought to a conclusion in as few actions as possible (see C‑IV, 3). In exercising its discretion the examining division must consider all relevant factors; in particular, it must balance the applicant's interest in obtaining a patent which is legally valid and the EPO's interest in bringing the examination procedure to a close in an effective way (in accordance with the principles set out in G 7/93).

Furthermore, the exercise of discretion to refuse amendments under Rule 137(3) must be reasoned (see T 755/96). The examining division also cannot refuse to admit amendments in advance (T 1105/96; T 246/08).

As an exception to Rule 137(3), paragraph (b) of Rule 164(2) provides for a right to amend the application in response to the results of any search under Rule 164(2). This means that applicants may make amendments of their own volition once in response to the communication under Art. 94(3) to which the search results under Rule 164(2) are annexed (see also H‑II, 7.4.1).

If an amendment is admitted, subsequent proceedings are based on the description, claims and drawings as amended. Admitting an amendment does not necessarily imply that the application as amended is allowable, i.e. free from any objection under the EPC.

In exercising its discretion under Rule 137(3), the examining division will take into account the circumstances of each individual case and the stage of the proceedings which the application has reached to date. A further important element is whether the applicant has already had sufficient opportunity to make amendments. In particular, amendments reintroducing deficiencies previously pointed out by the examining division and removed by the applicant are not admitted (see T 1326/11 and T 1064/04).

The applicant has to bear in mind that it is easier to secure an amendment at an earlier rather than at a later stage: the later amendments are filed, the more important the aspect of procedural economy becomes in balancing the interest of the applicant in obtaining a patent and the EPO's interest in bringing the examination procedure to a close (see T 951/97 and G 7/93).

On the other hand, amendments limiting a claim which is already considered allowable are normally admitted. The same applies to amendments improving the clarity of the description or claims in a clearly desirable manner (see T 1929/13).

If amendments clearly remedy a deficiency in response to the preceding communication, they are always admitted, provided they do not give rise to some new deficiency.[Art. 94(3); ]

A further factor is the amount of alteration to the application documents involved. Extensive reworking of the description or claims may be a proper response to highly relevant further prior art of which the applicant has only just become aware (e.g. either through further citation by the examining division or through knowledge obtained from another source). Regarding less extensive amendments, the examining division will adopt a reasonable approach, trying to balance fairness to the applicant against the need to avoid unnecessary delay and excessive and unjustified additional work for the EPO.

Additional reasons for not admitting amendments according to Rule 137(3) include the non-admittance of:

for reasons of procedural economy (taking into account the applicant's right to comment according to Art. 113(1)).

Additional limitations on possible amendments of the application may apply if the European or supplementary European search report was a partial one due to Rule 63 or restricted in accordance with Rule 62a (see H‑II, 6, and subparagraphs).[Rule 62a; Rule 63; Rule 137(5); ]

Further limitations may apply after a remittal by a board of appeal under Art. 111(2).

2.3.1 Examples of the exercise of discretion under Rule 137(3)