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Manual of Patent Practice

Intellectual Property Office
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Section 117: Correction of errors in patents and applications

Sections (117.01 - 117.31) last updated: July 2015.


This section is concerned with the correction of errors in specifications and in other documents filed in connection with patents and applications. Prescribed conditions are set out in r.105. (For the distinction between correction and amendment, see 19.03-19.04). S.117 and r.105 do not cover failure to file a document within a prescribed period; they are concerned solely with correcting errors in documents, and not with procedural errors or omissions, which are the province of r.107 (Klein Schanzlin & Becker AG’s Application [1985] RPC 241; Tokan Kogyo KK’s Application [1985] RPC 244). Subsections (3) and (4) were added by the Regulatory Reform (Patents) Order 2004, with effect from 1 January 2005.


S.117 does not govern correction of the Register nor of documents filed in connection with registration, for which see 32.14. If, however, an error in the Register has resulted from an error in a document which is subsequently corrected under s.117 then the Register will be corrected accordingly.

[ A request to correct an error or mistake under this section must be made in writing and identify the proposed correction.]

Section 117(1)
The comptroller may, subject to any provision of rules, correct any error of translation or transcription, clerical error or mistake in any specification of a patent or application for a patent or any document filed in connection with a patent or such an application.


r.105(1)-(2), r.49 is also relevant

Except in the case of a name (where correction must be requested on Form 20, see 16.23), a request to correct a document under this section must be made in writing clearly identifying the proposed correction. (The comptroller may require the filing of a copy of the defective document on which the correction is shown, and may request that it be shown in red ink.) For correction of an error in an address or address for service, see also 117.17. See 80.03-06 with regard to translations corrected under s.80(3).

[ A request to correct an error in a specification should be referred by the formalities examiner via the Formalities Manager to the case examiner. The Formalities Examiner should add a minute to the dossier for the case examiner and send the appropriate PDAX message to the examiner. If the request is allowable the correction should be effected; if this cannot readily be done on the existing documents and replacements have not been filed they should be asked for. The Formalities Examiner should create a working copy annotated appropriately and place a “P” against the documents for publication. If the application is a paper case, replacement drawings should be stamped as under 15A.06 and superseded drawings, other than any marked “not to be amended”, should be cancelled. ]


Although the request will normally be made by the applicant or proprietor, any person able to give evidence as to the occurrence of an error may request its correction.


If an examiner notices an apparent error of significance during substantive examination it should be drawn to the applicant’s attention. Exceptionally, as the wording of s.117(1) allows the comptroller to make corrections on his own initiative the examiner may make clearly allowable corrections of obvious minor errors but should inform the applicant that he has done so.


Provided the request for correction has been allowed before the completion of preparations for publication the application published under s.16 will be published as corrected (see 16.23) and the published document will bear a notice (see 16.29 that it embodies a correction made under s.117(1).

Correction of the specification



r.105(3) is also relevant

No correction may be made in a specification unless the correction is obvious (meaning that it is immediately evident that nothing else could have been intended in the original specification). This is construed as imposing a two-fold test:
(a) is it clear that there is an error, and
(b) if so, is it clear what is now offered is what was originally intended?

A very similar two-fold test was at the centre of judicial reviews under PCT r.91 in R. v the Comptroller-General of Patents ex parte Celltech Ltd [1991] RPC 475 and in Drazil’s Application [1992] RPC 479. These judgments may not be fully applicable to corrections under s.117 since there are differences in the wording between r.105 and PCT r.91 and s.117 is not one of those sections listed under s.130(7) as having the same effect as corresponding provisions in the EPC, CPC and PCT. Rule 139 EPC has similar wording to r.105(3) but the Enlarged Board of Appeal of the EPO has decided in Decision G11/91 (OJEPO 3/93) that no correction can be allowed which would extend the disclosure. As indicated in 19.04, that limitation does not arise under the 1977 Act.

r.105(4) is also relevant

[ However, the test set out above does not apply where the error in the specification is connected to the delivery of the application in electronic form or using electronic communications, i.e. where an error was caused by the conversion from one electronic format to another, a correction to the specification should be allowed.]

[ If it appears to the case examiner that the alteration sought does not meet the tests for a correction but it appears that it would be allowable as an amendment under s.19 or s.27 this course may be suggested to the applicant. ]


In order to pass the first test it must be apparent on the face of the documents that something is amiss. This would clearly be the case if a passage did not read on, or if a page were missing. It is not, however, necessary that the error be as readily apparent as this; the notional addressee of the specification is a person who is reading the document with the intention of extracting all the teaching from it, and who is aware of everything of common knowledge in the art concerned. For example, while a casual reader might not realise that the quoted serial number of another patent is incorrect, the notional reader will turn up every reference as he comes to it, and it will then be apparent (if for example the patent apparently referred to relates to completely different subject-matter) that the reference given would not have been intended. Likewise if an error is made in giving a known physical parameter, for example a eutectic temperature, the reader may be deemed to recognise this, even if he has to refresh his memory from a reference book. Also, a knowledge of all the contents of the open part of the file of the application should be attributed to the reader, so that, for example, a discrepancy between the specification and an otherwise similar priority document should be regarded as enough to put the reader on enquiry. If, however, the specification makes technical and linguistic sense, then it is not immediately evident that this would not have been what was originally intended, so that, irrespective of what is proposed as the correction, it cannot be said that nothing else than what is offered would have been intended. In such a case the matter cannot be dealt with as the correction of an error.


Although it will sometimes be apparent on the face of the documents what the correction should be, this will not generally be the case if for example the error lies in an omission or in an incorrect document reference or numerical data. It is not however necessary that the reader be able to correct the error unaided; in considering an offered correction regard must be had to the view which the fully-informed and inquisitive skilled reader would take of the documents originally filed and the most likely solution to the difficulty apparent to him from them. Often the correct version will be unique and will be apparent from the documents filed at the time at which the application was made. Otherwise evidence will be necessary to establish that the correction offered is what was originally intended. In Dukhovskoi and Others Applications [1985] RPC 8 where it became accepted during the proceedings that the error was apparent, the Patents Court held that the original document which it was asserted has been mistranslated (which was neither the priority document nor one of the documents available to the Office at the date of filing) could be considered when the application for correction was made and, with the aid of a dictionary, could establish that the correct translation was what was suggested by the correction. A priority document filed later than the date on which the declaration of priority was made (see 5.08 to 5.11) may be taken into consideration provided that it can be shown it was intended at the time the declaration of priority was made to claim priority from that document rather than some other application. This will be shown if its file number was included on the date the declaration of priority was made. If however this number is supplied later (as under rule 8(1), it may be) and there is a reasonable doubt as to its veracity, suitable evidence may take the form of a sworn statement from the applicant or an extract from the official Gazette of the country of filing indicating that it was the only application filed by the applicant on the date in question. A later-filed document may also be used to show that a particular process or construction is well-known in the art and could be assumed to be known to the skilled reader. The expression “immediately evident” is however taken as requiring that, when all the evidence is considered, it is abundantly clear that nothing else other than what is now offered as the correction was originally intended. It is not sufficient merely to show that, on balance of probabilities, the correction offered is the most likely version.

[ Borderline cases under r.105(3) and any where the strict application of the rule would apparently lead to a ridiculous result should be referred to the Divisional Director. ]


Section 15(8) states that s.15(6) and (7) in relation to “missing parts” do not affect the comptroller’s discretion under s.117(1) to correct an error or mistake. Thus, if all of the requirements of s.117 and r.105 have been met (see 117.03-09), it is possible for the comptroller to allow a missing part to be filed as a correction under s.117(1) without redating. Applicants should be asked to indicate, in writing, whether any drawing(s) filed with such a request under s.117 is/are to be regarded as a filing where ss.15(5) to (7) apply, should the s.117 request be disallowed.


A request to correct an error in the specification of a European patent (UK) should be dealt with in the same way as in the case of a patent granted under the Act. However, the comptroller does not entertain a request for correction of the text of a European patent (UK) under s.117 if the EPO has already allowed the correction. The formal publicising of such a correction is also solely a matter for the EPO. If a request under s.117 to correct an error in the specification of a European patent (UK) is received before the nine months allowed for opposing the patent has expired or when there is an opposition outstanding, the possibility exists that the specification may be amended before the EPO. In such circumstances the agent is given the option of either (a) staying the request until the opposition period has expired or the opposition proceedings have been settled or (b) proceeding with the request to correct under s.117 on the understanding that the desired correction may be negated as a result of subsequent amendment before the EPO. If it is not possible to determine the allowability of the correction solely by reference to the published specification, the applicant should be required to furnish the necessary documentary evidence, for example copies of any relevant documents indicating the “as filed” state of the application.

[ Where a request under s.117 is received to correct a European patent (UK), Litigation Section will check on the EPO online file inspection service in order to ascertain (a) whether the period allowed for opposing the patent has expired and whether any opposition was entered and (b) whether any application for central amendment of the patent has been made and whether any amendment has been allowed. Where necessary the proprietor or agent will be given the option of staying the request. If the applicant is to be given the option of staying the proceedings, the requested correction should be scrutinised by a Deputy Director and any prima facie objection to it should be communicated to the applicant in a letter giving him the choice on stay. A request to correct a document in a European patent (UK) other than the specification will be referred by Litigation Section to the Deputy Director].

Correction of translations of the specifications of European patents (UK)


A request to correct a translation of the specification of a European patent (UK) filed under s.77(6)(a) should also be dealt with in the same way as a patent granted under the Act but unlike a request to correct the text of a European patent (UK), it should never be deferred pending the expiry of the opposition period. An additional consideration is whether the correction requested properly comes under s.117 or s.80(3). If the correction of the translation would seem to broaden the protection conferred by the patent or application, it should be made under s.80(3) in accordance with the procedure in 80.03-06, for which purpose a fresh application on Form 54 is necessary. Correction of the translation will not be appropriate where the error lies in the specification of the European patent (UK) but the translation is nevertheless a correct representation of the incorrect text. In such cases a request should be made to correct the specification. If this necessitates a fresh verified translation then such a translation should be filed pursuant to r.113(1).

[(i) The procedure for correction of such a translation under s.117 generally follows along the same lines as for correction of UK national patents after grant, as follows.

(ii) After stamping and scanning, the request for correction is passed to Litigation Section for the request for correction to be noted in the Register and advertised in the Journal.

(iii) Litigation Section will send the file to the Deputy Director for consideration as to whether the correction requested properly comes under s.117 or s.80(3) and whether or not the correction is allowable.

If it is decided that s.117 is appropriate, the considerations as to the allowability of the correction set out in 117.07-117.10 apply. However, if the requested correction would seem to broaden the protection conferred by the translation the correction should be made under section 80(3). In this case a minute should be created to that effect, in a form suitable for communication to the agent/proprietor, and a PDAX message sent to Litigation Section for preparation and issue of a letter embodying the minute. The letter should also invite the agent/proprietor to initiate action under s.80(3) by filing Form 54 with appropriate fee, see 80.03-06.

(iv) Subsequent procedure is basically as in the second square bracket paragraph of 117.14 except that:
(a) unless the corrections are of minimal extent, Litigation Section will call upon the proprietor to provide, within a specified period, a new translation incorporating the corrections instead of correcting the original copy of the translation,
(b) Litigation section should ensure that the file copy is updated accordingly and that a copy of the corrected translation is also sent to the British Library, and
(c) since the correction relates to the translation of the specification, it is not necessary for Publishing Section to issue a C publication.]

Procedure before publication

(See also 117.06)




If an examiner notices a clerical error which would be likely to impede the understanding of a specification when published he should inform the applicant or agent. However, the initiation of a correction is a matter for the applicant, and if he does not respond the matter should be deferred until substantive examination. Publication should not be unduly delayed. Purely formal editorial matters, such as the re-arrangement and renumbering of accidentally transposed pages, may be effected by the examiner with the applicant’s or agent’s agreement, provided that the nature of the error and its correction are beyond reasonable doubt.

[ If a page of text appears to be missing from the specification the formalities examiner should draw this to the attention of the case examiner. If the case examiner considers that the matter may be rectified as a correction he may invite the applicant to make a request for correction. In no case should action be taken which would be likely to provoke a request to correct if it appears that such a request would not be allowable. ]

Procedure between publication and grant


Any request to correct an error received after the completion of preparations for publication of an application but before grant should be considered as soon as possible and not deferred until substantive examination, for example. An erratum should be issued once the correction has been allowed. Where there is doubt whether the desired alteration is intended to be by way of correction or amendment (see 19.03-19.19), the situation should be clarified with the applicant.

[ Where such a correction is considered allowable, the examiner should create a minute addressed to Formalities, noting that a correction has been allowed under s.117, and requesting that an erratum is issued. ]

Procedure after grant


The examiner to whom the request is referred must consider it according to the tests set out in paragraphs 117.07 to 117.09. He must also consider whether it is necessary to advertise the correction (see 117.23-117.24). When allowed, the correction is published as a C publication. The C publication is a front page either with a schedule of the corrections on the reverse or associated with a new corrected specification if one has been filed, the procedure being the same as for a C publication for amendment of a granted specification, see 27.20. A C publication is not normally issued for correction of printer’s errors or of errors in the bibliographic information on the front page of a published specification, these being dealt with by issuing errata. However, if a C publication is being issued for other reasons, any such errors are corrected at the same time.

[ A request received after grant is handled by Litigation Section who arrange for the preliminary notice of the request to appear in the Journal (see 117.23). If it relates to an error in a specification it should be referred to the Deputy Director of the group dealing with the relevant subject matter, who may refer it to a member of his group. Any objections to the proposed correction should be set out in terms suitable for embodiment in an official letter which is issued by Litigation Section. (See also 117.07).

[ When the examiner is satisfied that the correction is allowable he should so report and send a PDAX message to Litigation Section. The Deputy Director should instruct Litigation Section as to whether or not the correction should be advertised. If the correction is not being advertised, or if the period allowed for opposing the correction (see 117.25) has expired, or if any opposition has been concluded, Litigation Section should assemble the specification. The corrections should be checked in the examining group before the Deputy Director confirms the certificate should be applied. The case should then be returned to Litigation Section who should notify the person making the request that it has been allowed, date the certificate with the date of such notification, arrange for the outcome of the s.117 proceedings to be entered in the register and advertised in the Journal, create a minute and send a PDAX message to Publishing Section for issue of a C publication (and also an erratum as in 117.06 if the correction is applicable to the A publication as well as to the B publication). ]


If a request to correct is received after the issue of the letter informing the applicant that a patent has been granted but before the date of publication of the patent, the applicant should be informed that consideration of the request is deferred until after publication. Following publication of the patent, the post-grant procedure as set out in 117.14 should then be followed.


If proceedings to correct a patent are initiated or are outstanding whilst an action for revocation of the patent is pending the comptroller may decide whether the s.117 proceedings are to be stayed or resolved.

Correction of the request for grant


r.49 is also relevant

If the applicant’s address or address for service was given incorrectly on Form 1 then it may be corrected by means of any suitable written notification. However, a request under r.49(1)(a) to correct a name must be made on Patents Form 20. If, however, the name was correct at the time of filing and has changed subsequently then alteration of the form to reflect this must be effected either as an amendment under s.19 (if more than just the name requires amendment) or a correction to the register under s.32(2)(d) (if only the name has changed), see 19.05-19.07 and 32.06. If there are reasonable doubts about whether the correction should be made, the comptroller should inform the person making the request of the reason for his doubts and ask that person to file evidence in support of the request, i.e. proof that the name was entered incorrectly and that the name that is to replace it is the name that the applicant always intended entering on the form. If a request to correct an error or mistake in a name is allowed the change is effected in the same way as in the case of an amendment (see 19.07).

[ The procedure is the same as that described for amendments in paragraphs 19.06 -19.07.]


A request to correct the title of the invention should be considered in the same way as a proposed correction of the specification (see 117.07-117.09).


r.86, r.87 is also relevant.

A declaration of priority at part 5 of Form 1 (or a claim in part 6 of that Form, or a declaration in part 6 of Form 3) may be corrected provided the Office is satisfied that the discrepancy was due to an error in translation or transcription or a clerical error or mistake. If the error lies in the details of the priority document or earlier application or patent then this document itself may be sufficient evidence. Otherwise, where there is reasonable doubt that the alleged mistake is in fact a mistake (or where there is reasonable doubt as to the veracity of any matter contained in the request or of any document filed in connection with it) evidence may be requested which demonstrates that what is now proposed was the applicant’s intention at the time of filing. It is, however, a condition of Rule 5 of the Patent Law Treaty that when such evidence is requested, the nature of the doubt must be communicated to the applicant, and this practice should always be observed. A copy of the applicant’s instructions to his agent may suffice; otherwise sworn evidence should be asked for before the request is given further consideration, and a period of two months should be specified for reply. Any priority document or translation in support of a new declaration must be filed within the period prescribed. In Payne’s Application [1985] RPC 193 the applicant sought to delete the two earliest claims to priority by way of correction but, before the matter was decided, the applicant was informed by the Office that the application had been treated as withdrawn through failure to file the request for search. The applicant subsequently argued that the correction should be allowed (in which case the search request could have been filed in time) notwithstanding that the application had ceased to exist. It was held in the Patents Court that section 117 could not be invoked to overcome this mandatory requirement, see 15.56.

[ A request to correct the declaration of priority should be referred by the Formalities Examiner via the Formalities Manager to the divisional Head of Administration, who will, if the request is allowable, correct Form 1.

PDAX dossiers: Form 1 should be corrected using the Enhance function in PDAX, and an action added to the dossier. The Head of Administration should add a minute to the dossier and ensure the appropriate OPTICS action is carried out.

Paper cases: Form 1 should be corrected in red ink, initialled and dated, and the appropriate OPTICS action carried out. The Formalities Manager should then correct the priority details on the front of the shell.

The applicant should be informed of the allowance of the request. If the request has been received before the completion of preparations for publication, a minute and the appropriate PDAX message should be sent via the Examination Support Officer outlining the publication instructions. If the application is a paper case, an appropriately-completed “Notices for front page of ‘A’ document” form (see 117.06) should be placed on file. If the request was received later than this, arrangements should be made for an erratum to issue in respect of the A document (and B document if appropriate). ]


r.6(2) is also relevant

Where the only matter to be corrected is the priority document file number quoted on Form 1 or Form 3, then no evidence is required provided the error is notified to the Office within the period which is allowed for supplying this number. (For the case where the details on Form 1 are correct but there is a discrepancy in the priority document, see paragraph 15A.16).


r.3 is also relevant

Since correction is deemed to have effect ex tunc, a correction of the declarations of priority may affect the declared priority date even if the change was effected after the completion of preparations for publication.

Other corrections


r.49, r.105 is also relevant

An error in Form 7 may be corrected after the end of the period allowed for filing this form following a request in writing, except for correction of a name which must be made on Patents Form 20. (For effecting a change in Form 7 before the end of this period, see 13.14). If there are reasonable doubts about whether the correction should be made, the comptroller should inform the person making the request of the reason for his doubts and ask that person to file evidence in support of the request. A copy of the corrected Form 7 should be sent to each inventor. The decision in Payne’s Application (see 117.19) means that s.117 cannot be invoked to overcome the mandatory requirements of s.13(2) (see 13.14).

[ A request to correct the inventor details on Form 7 should be referred by the formalities examiner via the Formalities Manager to the Assistant Head of Administration, who will, if the request is allowable correct the details on Form 7 using the “Enhance” function on PDAX, add a minute to the dossier and annotate Form 7. If the application is a paper case, the Assistant Head of Administration should, if the request is allowable, correct Form 7 in red ink, initial and date the correction and carry out the appropriate OPTICS action. Where an inventor has been added or deleted after the completion of preparations for publication, the formalities examiner should send a message to Publishing Section for issue of an erratum. ]


s.14(10) is also relevant

An error or mistake in a withdrawal of an application may be corrected upon request in writing. A written explanation or evidence will be needed in support of the request.

Advertising a correction


r.75, r.105(5) is also relevant

Notice of a request for correction of an error or mistake in the withdrawal of a published patent application will be published by advertisement in the Journal –see 117.31. In all other circumstances, except where the comptroller determines that no person could reasonably object to the correction, the fact of a request for correction and the nature of the proposed correction are advertised in the Journal. Preliminary notice of a request made post-grant is inserted in the Journal, and the proposed correction should be advertised if it would alter the meaning or extend the scope of the specification of a granted patent, or if the rights of a third party could be adversely affected. Other corrections sought before grant are not normally advertised.

[ For procedure post-grant see under 117.14. Corrections pre-grant are not normally advertised and the procedures described under 117.13 or 117.13.1 should be followed.]


r.75 is also relevant

When it appears to the Office that a correction may be allowed the applicant should be so informed and if appropriate the correction should be advertised. If the period allowed for opposing the correction (see 117.25) has expired without any opposition being filed the correction should then be effected as soon as possible. This must be by order for certain corrections of withdrawals –see 117.31. On the other hand, if agreement is not reached with the applicant, a hearing should be offered. If the applicant requests to be heard he should be informed that an ex parte hearing will be appointed subject to advertisement of the proposed correction and the absence of opposition.

[ For procedure see under 117.14. ]

Section 117(2)
Where the comptroller is requested to correct such an error or mistake, any person may in accordance with rules give the comptroller notice of opposition to the request and the comptroller shall determine the matter.


r.75, r.76(3), r.108.(1) is also relevant

Any person may oppose a correction; there is no need for an opponent to show a locus standi. Notice of opposition should be given on Form 15, which should be filed within four weeks of the date of advertisement of the correction in the Journal; this period may not be extended. The Form should be accompanied by a copy thereof and by a statement of grounds (in duplicate). This starts proceedings before the comptroller, the procedure for which is discussed at 123.05 – 123.05.13.




s.74(2) is also relevant

The notice of opposition and supporting statement must be directed solely to the allowability of the correction. In particular, the validity of the patent may not be put at issue.


r.82 is also relevant

The comptroller may give such directions as he thinks fit with regard to the subsequent procedure. If a form of correction acceptable to the parties and the Office is not arrived at, the matter will need to be decided at a hearing.


Where an opposition to the correction has been properly launched by the filing of Form 15 accompanied by a supporting statement, but the opponent subsequently withdraws at any stage, the comptroller nevertheless takes account of matters raised by the opponent in deciding whether the correction is allowable. If no agreement is reached with the applicant, an ex parte hearing is held.

[The procedure is the same as that described in 27.31.]

Section 117(3)
Where the comptroller is requested to correct an error or mistake in a withdrawal of an application for a patent, and
(a) the application is published under section 16 above; and
(b) details of the withdrawal were published by the comptroller;

the comptroller shall publish notice of such a request in the prescribed manner.
Section 117(4)
Where the comptroller publishes a notice under subsection (3) above, the comptroller may only correct an error or mistake under subsection (1) by order.


Subsections (3) and (4) were added by Article 17 of the Regulatory Reform (Patents) Order 2004. These provisions relate to the power of the comptroller, alluded to in section 14(10), to correct an error or mistake in a withdrawal of a patent application (see 14.209). This is effective from 1 January 2005 and applies to applications irrespective of whether their filing date is before or after that date.


r.105(6) is also relevant

These provisions ensure that in the case of a published application whose withdrawal was published in the Journal, the request for correction of that withdrawal will likewise be published. This will be done by advertisement in the Journal and an entry in the register. The advertisement concludes the period referred to in s.117A(4), see 117A.02. If the correction is made it must then be effected by order.