Manual of Patent Practice

Section 15A: Preliminary examination

Sections (15A.01 - 15A.26) last updated: October 2026.

Section 15A: Preliminary examination

15A.01

This section sets out the conditions necessary for an application to proceed to preliminary examination, makes provision for carrying out the preliminary examination and for reporting the results. Rules 23, 24 and 25 are particularly relevant to this section.

Information security: a reminder

15A.01.1

(s.118(2) is also relevant).

The preliminary examination of UK patent applications is carried out before A publication, and so most of the guidance in this section relates to pre-publication actions. Before A publication, the application, the preliminary examination report, and any other documents or information concerning the content of the application (other than that prescribed under s.118(3)) must be protected and must not be communicated to anyone outside the Office other than the applicant or their designated representative – see 118.16- 118.16.1 for further guidance on these issues.

15A.01.2

More generally, in all cases, whether pre-or post-publication, it should be ensured that any communications (including telephone conversations) are directed to the intended recipient.

[Where correspondence from the Office is reported as never having arrived at its intended destination, or is reported as being misdirected or delayed, this fact should be recorded by notifying the relevant formalities group with any relevant details. For misdirected correspondence, an Incident and Breach report should be raised.]

Section 15A(1)

The comptroller shall refer an application for a patent to an examiner for a preliminary examination if - (a) the application has a date of filing, (b) the application has not been withdrawn or treated as withdrawn; and (c) the application fee is paid.

15A.02

s.15(10)(c) is also relevant

The payment of the application fee will initiate preliminary examination. When applying for a patent by paper using combined Forms 1, 7, 9A and 10, there is provision to pay the application fee in section F of the form, although it is not a requirement for the fee to be filed with this form. If the application fee is paid independently of the combined Forms 1, 7, 9A and 10, it is suggested that it be accompanied by non-statutory form AF1.

15A.03

The time allowed for filing the application fee is prescribed in r.22(7), (see 15.51 - 15.53). The preliminary examination should be carried out by the formalities examiner as soon as possible after the application fee has been paid and a letter should be issued (see 15A.20) if there are any outstanding objections.

[ When the formalities examiner identifies a procedural requirement is outstanding, a letter should be sent to the applicant. A note on the Timeline may also be addressed to a specific person, for example the search examiner, and may be by way of explanation or reminder.]

[When before publication, all the formal requirements have been met, the formalities examiner should add a minute to the timeline explaining that no preliminary examination report has been created.]

[Where an application is identified as a ‘no case’, the PAU examiner will issue a ‘No Case Letter’, informing the applicant of the requirement to file a technical description in order to establish a filing date. Where fees have been filed with such an application, the unspent fees should be refunded and the applicant informed either by phone or in the ‘No Case Letter’. PAU desk notes provide further guidance on the process.

Section 15A(2)

On a preliminary examination of an application the examiner shall - (a) determine whether the application complies with those requirements of this Act and the rules which are designated by the rules as formal requirements for the purposes of this Act; and (b) determine whether any requirements under section 13(2) or 15(10) above remain to be complied with.

15A.04

(r.23(1) is also relevant).

The formal requirements are those designated by r.25(1), namely the requirements of r.12(1) and r.14(1)-(3). The formalities examiner should therefore establish whether the application for a patent has been properly completed (see 14.04 - 14.25) indicating an address for service (see 14.04.13), and whether or not the drawings and other documents comply with the formal requirements of r.14 (see 14.26-14.57). The preliminary examination should also establish whether action under s.15(3) is necessary, and whether the requirements of rr.6-9 (see 15A.13 -15A.17) and rr.10(1) and 10(2) (see 15A.11 - 15A.12) have been met. If any requirements in relation to s.13(2) or 15(10) are outstanding these should also be determined. If it is established as a result of this preliminary examination that there is no outstanding objection, this should be recorded in a minute on the timeline.

(r.13(2)-(7) is also relevant).

[ Where the specification of a patent application concerning biological material discloses a sequence, the formalities examiner should also check that it includes a sequence listing, in accordance with rule 13(2). If a sequence listing has not been provided then the preliminary examination report should specify a period of 2 months from the date of the report within which the applicant must provide the sequence listing. If a sequence listing has been filed, but is found to be non-compliant with WIPO standard ST26, then the preliminary examination report should specify a period of 15 months from the earliest date of the application within which the applicant must provide a replacement sequence listing. Although neither of these are formal requirements designated by r.25(1), the comptroller may refuse the application if the sequence listing is not provided within the period specified. If there is any doubt as to whether an application falls under these circumstances then the formalities examiner should consult the examiner.]

The specification

15A.05

If the pages of text of the specification do not conform with the formal requirements of r.14, the formalities examiner should itemise the outstanding requirements (see 15A.20).

[ Given that some private applicants may add matter or carry out extensive redrafting of the specification, objection under r.14 against a private applicant’s specification should not normally be raised. If unavoidable, any necessary typing or other essential remedial action for the purposes of s.16 publication may be undertaken in the Office unless this is clearly impossible (see 14.30). Where such remedial action has been taken, the appropriate notice should be inserted on the front page (see 16.29). The applicant should be advised of the retype and a copy of the typed pages included.]

15A.06

(r.14(3) is also relevant).

If the drawings are formal, that is to say, they comply with the formal requirements, then, provided they were present on the filing date of the application, they should be annotated appropriately in the All Right Documents. Any additional copies should also be annotated appropriately. (For the procedure when formal drawings are filed late following the initial filing of informal drawings, see 15A.22; for the case where a drawing not present in any form on the filing date is subsequently filed, see 15A.23).

15A.07

If the drawings are informal, that is, if they fail to comply with the formal requirements of r.14, a report to this effect should be made, detailing the deficiency unless it is clear that the drawings filed were intended only as an informal version. Informal drawings should be annotated appropriately in the All Right Documents.

15A.08

[deleted]

15A.09

A drawing containing formulae which appear in the text of the specification is rarely needed. If such a drawing has been filed but is not to be used in publishing the A document, no action is necessary and it should be left on file. If the drawing is required, if it complies with the Rules it should be annotated appropriately. Such drawings do not need to be in duplicate, and any further copies should also be annotated appropriately. Any discrepancy between the drawing and the formulae in the text should be drawn to the attention of the search examiner. If, in the search examiner’s opinion the text is wrong, and the drawing correct, and the drawing was present on the date of filing the application, no action should be taken before substantive examination; the drawing is used in preparing the published application and may be used for the abstract. If the search examiner considers that the text is correct and the drawing wrong, or cannot form an opinion, the applicant should be asked to provide a drawing agreeing with the text. (If formula drawings were supplied later than the filing date of the application, see 15A.22).

[ If the search examiner is sure that, where there is a discrepancy, the text is correct and the drawing wrong, they may correct the drawing and so inform the applicant. Publishing Section should be given suitable instructions where a formula drawing is to be used in producing the A document.]

15A.10

(r.25(3) is also relevant).

If the application is an international application (UK) the formal requirements of rr.12(1) and 14 are regarded as having been met if the requirements of the corresponding rules of the PCT have been met. Rule 12(1) is equivalent to r.53.1 PCT and r.14 is equivalent to r.11 PCT. According to section 81(3)(c), any document filed with the European Patent Office under provisions of the EPC corresponding to sections 2(4)(c), 5, 13(2) or 14 shall be treated as having met the requirements of those sections. Rule 12(1) is equivalent to r.41(1) EPC and r.14 is equivalent to r.45(1),(2),(3) and r.49 EPC.

Statement of inventorship and derivation of right to grant

15A.11

(r.10(4) is also relevant).

The formalities examiner should determine whether there are inventors who are not named as applicants, or applicants who are not inventors, and report whether inventorship and derivation of right details have been properly submitted (either through the One IPO Patents Service, or using Section D of the combined Forms 1, 7, 9A and 10 when filing by paper).

15A.12

(r.10(3) is also relevant).

If it is found that the inventorship and derivation of right details are outstanding or if there appears to be a defect, and the end of the 16 month period (see 13.11) is near, the applicant or agent should be notified at once. If an applicant is required to provide inventorship and derivation of right details on the basis of there being inventors who are not named as applicants, or applicants who are not inventors, and the applicant fails to provide this information within the prescribed period, the application is taken to be withdrawn (see 13.13). The prescribed period in the case of a divisional application is determined by r.21 - see 15.26).

Priority documents

15A.13

(r.24(1), s.120(2), r.7, r.24(2)-(3) are also relevant).

If a claim to an earlier priority date (declaration of priority) has been made, either through the One IPO Patents Service or in part 3 of Section B of the combined Forms 1, 7, 9A and 10 when filing by paper (see 14.04.14), the formalities examiner should determine whether the filing date of the application is within the period of 12 months from any priority date so declared (always remembering that if the period of 12 months expired on an excluded day or on a day which is certified as one on which there was an interruption under r.110(1), see 123.43, the period is extended to include the first following day which is not excluded or certified, and the period may also be extended under r.111, see 123.46-47). If it is not, the applicant should be informed that the claim to priority is not valid and be advised if a request for late declaration of priority under s.5(2B) may be applied for. Where it is not possible to claim the priority date declared, the applicant must provide a corrected date for which a valid priority claim is possible within two months of being notified by the formalities examiner, otherwise the declaration will be disregarded. If the declaration was made via the One IPO patents service, data validation prevents the applicant from making a claim to an invalid priority date.

15A.14

(r.112 r.8(2), PR Sch. 4, Part 2 are also relevant).

The formalities examiner should determine whether the file number of the or each application from which priority is claimed has been supplied, either when the application was initially filed, or subsequently. If a copy of the priority claim application is available to the office the formalities examiner should obtain a copy of the application for import into the All Right Documents (see 15A.18-15A.19). Where the priority claim application is not available the formalities officer should determine if a certified copy of the application has been filed within the prescribed period of 16 months (extendible in accordance with r.108(2) or (3) and (4) to (6), [see 123.34-41]) from the earliest declared priority date. Where priority is claimed from more than one application, all the certified copies must be filed within this period. Where no certified copies of the application have been filed the formalities examiner should report this and should also report if an application from which priority is claimed is not an application for a patent under the Act, an international application filed at the Office or any other application supplied to the Office in support of a declaration of priority on another application made under the Act [(see 15A.20)]. (For the periods allowed for filing priority documents when the application in suit is one for a European Patent (UK) converted under s.81, or is an international application see 5.10; for the periods in respect of a divisional application see [15.23].

15A.15

(r.8(1) is also relevant).

When such a copy is filed, it must be established that it is of a “relevant application” (see 5.30) from which priority can legitimately be claimed, and that the document is consistent with the details given in the declaration of priority. If there is a discrepancy an explanation should be sought from the applicant. If there is an error in the declaration of priority, an application to correct it should normally be made in writing. If the wrong priority document has been filed, or if details on it are clearly incorrect, a replacement (duly certified) should be requested and must be filed before the end of the prescribed period; if it is filed later, a written request for its admission as a correction under s.117 should be filed. If the priority document meets the requirements of r.8, a confirmation of receipt should be issued.

[ If there is a discrepancy between the declaration of priority and the priority documents the agent should be contacted by telephone (followed by written confirmation) to establish where the error lies. If only the file number on the declaration of priority is wrong then it may be corrected in the office, provided that the error is notified within 16 months of the earliest declared priority date, since the applicant is allowed to supply the file number at any time within this period. If the fault lies in the priority document and the prescribed period has already expired, the matter must be referred via the Formalities Manager to the Examination Support Operations Manager. ]

15A.16

If a page of text or drawing is apparently missing from the priority document the formalities examiner should ask the applicant whether or not the document is in agreement with the application, of which it purports to be a copy, as filed. If it is, no further action is necessary. If it is not, a replacement (duly certified) should be requested if the prescribed period has not expired. If that period has expired, the applicant can seek the admission of such a replacement as a correction under s .117.

[ If the priority document is deficient and the prescribed period has already expired, the matter must be referred via the Formalities Manager to the Examination Support Operations Manager. ]

15A.17

s.5(2), r.3 r.26(1) are also relevant

If, after 18 months from the earliest declared priority date, any required certified copy of a priority application has not been filed, the claim to priority in respect of that application is relinquished and the application will then proceed with its own filing date as priority date, or, where not all of several declared dates have been relinquished, with the earliest remaining priority date. Time limits and other dates, including the date on which publication is due, are reckoned from the new priority date. The applicant must be notified of the loss of any declared claim to priority and of the reason for this. Even if a claim to priority is relinquished (see 19.11), any related priority documents should be kept open for public inspection under s.118.

[ The appropriate standard letter should be issued warning of the intention to cancel the declaration or date of priority, and giving two weeks for any observations which might justify extension of the relevant period under r.108(3). In the normal case, after the two weeks has ended, the application should be referred to the Formalities Manager with an explanatory note added to the Timeline of the relevant case. The Formalities Manager will authorise the cancellation of the relevant priority details, add an explanatory note on the Timeline of the relevant case, and carry out, or arrange for the priority details to be updated on the Right. On a PCT application, the Formalities Manager will add an explanatory note on the Timeline of the relevant case, amend the WIPO print and NP1, and carry out, or arrange for the priority details to be updated on the Right . The formalities examiner must also inform the applicant by issuing letter LFH.]

[Deleted]

[ A note on the Timeline of the relevant case should direct the search examiner’s attention to the new priority date. ]

Priority claimed from an application filed at the Office

15A.18

If priority is claimed from a UK application, an international application filed at the Office or any other application supplied to the Office in support of a declaration of priority in a UK application, and the UK or international application has been withdrawn by the applicant or has been treated as withdrawn because the period prescribed by r.22(2), (together with a two month extension possible under r.108(2)) has expired without the request for search and the search fee being filed, documents may be transferred from the earlier application to serve as priority documents for the application in suit. When priority is claimed from an earlier UK application itself only documents present on the filing date of the earlier application may be so transferred; in particular, later filed claims or late-filed drawings may not be transferred.

[ In the case of a UK application the documents to be transferred are a copy of the combined Forms 1, 7, 9A and 10 (if the earlier application was filed on paper) and a copy of all other documents (and only those documents) submitted on the filing date of the earlier application. Care must be taken to ensure that there still remains on the file of the earlier application a complete set of documents representing copies of those transferred. Thus, in accordance with the above:-

the claims, abstract and drawings thus transferred must be those submitted on the application date. If none was filed on the application date no such transfer can occur; claims, abstract, or drawings filed after the application date (including formal drawings following initially-filed informal drawings) must not be transferred.

[ The priority document(s) should be annotated in the All Right Documents to advise the examiner as to whether the/each priority application has been searched.]

15A.19

[deleted]

Section 15A(3)

The examiner shall report to the comptroller his determinations under subsection (2) above.

15A.20

s.15A(2)(b) r.23(2) are also relevant

A letter should be issued following the preliminary examination setting out any objections arising therefrom. If the specification does not comply with r.14, or if any other formal requirement has not been met, the report should set out the precise grounds of objection. If it is clear that drawings which are informal are only intended as such, a statement that formal drawings should be filed will suffice. The applicant should be requested to rectify these deficiencies within 15 months of the priority date or, where there is none, of the filing date. If this period has already or nearly expired a period of two months should be allowed for compliance. If any other matters are outstanding, for example, if a priority document has not been filed and the time for filing it has not expired, or if a statement of inventorship has not yet been submitted, a reminder to this effect should be included in the report.

[ It is usual for any objection arising out of the preliminary examination to be conveyed to the applicant by standard paragraphs and issued directly by the formalities examiner. If however the circumstances demand it, any outstanding procedural requirements may be communicated to the applicant by “first” letter or by telephone followed by a confirmatory telephone conversation report. A first letter must be authorised by the Formalities Manager and will issue under their name. If, exceptionally, an outstanding formal requirement is conveyed for the first time by a communication using other than standard paragraphs, that communication must specify a period in which the applicant should comply with the requirement: it must also state that unless the applicant complies within the period specified, the comptroller may refuse the application after giving the applicant an opportunity to be heard in the matter. ]

[ A copy of a standard letter, of a telephone conversation report or of a first letter must be made open to public inspection. ]

15A.21

When replacement pages of text are filed, the formalities examiner should check that they are in exact conformity with those originally filed and that they comply with the formal requirements and should incorporate them into the application. The published application should carry a notice (see 16.29) stating that it takes account of replacement documents filed later than the application. If, however, the original text was illegible (as distinct from merely difficult to read) the matter should be referred to the search examiner (see 16.09).

[ If the replacement claims and description are acceptable, they should be annotated appropriately as the latest versions in the All Right Documents. See also o 15A.22. ]

15A.22

When formal drawings are filed, whether or not in response to an Official request, on an application where the drawings present on the filing date were informal, they should be checked by the formalities examiner for conformity with the informal drawings. Any discrepancy which appears prima facie (that is, without requiring undue investigation) to be material should be resolved before publication. Otherwise, the matter can be deferred for resolution at the substantive examination stage (see also 18.08). The consideration of discrepancies in formal drawings is a matter for the search examiner. The drawings should be annotated as in 15A.06 (the originally-filed informal drawings being regarded as a third copy). The published application should bear a notice (see 16.29) stating that the original drawings were informal and that the published drawings have been prepared from a later-filed formal copy. If formula drawings (see 15A.09) have been filed later than the filing date of the application and are to be used in producing the published application the formalities examiner should check that they agree with the formulae in the specification, any discrepancy being reported to the search examiner, and instructions for publication should be provided to include a notice that such drawings were filed late.

[ When replacement formal drawings are received the formalities examiner should check that they are identical to the informal drawings on file. Once the formalities examiner is satisfied that there is no discrepancy between the drawings and that all other requirements are met, the application should proceed to publication at the appropriate time without further referral to the search examiner (assuming the search report has issued). However, the search examiner should be consulted if the formalities examiner is unsure as to whether the later filed formal drawings are identical to those originally filed or has any doubt that what purportedly has been filed are formal or replacement drawings. Responsibility for deciding to raise the matter of any discrepancy with the applicant or agent will then rest with the search examiner, but it is the role of the formalities examiner to request replacement drawings if the search examiner determines they are needed. If the search examiner decides to defer until substantive examination the question as to whether any such discrepancy is material, they should add a note to the Timeline of the relevant Case to alert the substantive examiner to the situation. ]

(r.109 is also relevant).

[ If formal drawings or replacement pages are filed outside the period specified, an extension of time may be allowed. An automatic extension of two months to the specified period can be allowed on receiving a request in writing before the end of the period as extended. If the period has already been extended by two months a further extension of time may be allowed but this request must be accompanied by an explanation of the cause of delay. Any such request should be referred to the Formalities Manager for consideration. Any request made to extend a specified period after the two month automatic extension period has expired should also be referred to the Formalities Manager]

Section 15A(4)

If on the preliminary examination of an application it is found that- (a) any drawing referred to in the application, or (b) part of the description of the invention for which a patent is sought is missing from the application, then the examiner shall include this finding in his report under subsection (3) above.

15A.23

(r.18(2) s.15(6)(b) are also relevant).

The formalities examiner should check during the first preliminary examination that all drawings referred to in the description or claims were present (in either formal or informal versions) on the filing date of the application and that all the pages of the description are numbered consecutively. If such a drawing is missing or it appears that a page is missing this should be reported in the preliminary examination report. The report should state that the missing part should be filed within two months of the date of notification. Subsequent filing of missing drawings or pages will lead to the application being re-dated unless there is a claim to priority and an application to avoid re-dating is allowed see (15.07 TO 15.16). If any priority claim would become invalid because of re-dating, the following paragraph should be included in the Preliminary Examination report:

It should be noted that the application claims the earlier date of {DATE} under Section 5(2) of the Patents Act 1977. Therefore, the filing of the missing drawing(s) and the consequent re-dating of the application would render the claim to priority invalid.

Section 15A(5)

Subsections (6) to (8) below apply if a report is made to the comptroller under subsection (3) above that not all the formal requirements have been complied with.

Section 15A(6)

The comptroller shall specify a period during which the applicant shall have the opportunity- (a) to make observations on the report, and (b) to amend the application so as to comply with those requirements (subject to section 76 below)

Section 15A(7)

The comptroller may refuse the application if the applicant fails to amend the application as mentioned in subsection (6)(b) above before the end of the period specified by the comptroller under that subsection.

Section 15A(8)

Subsection (7) above does not apply if- (a) the applicant makes observations as mention in subsection (6)(a) above before the end of the period specified by the comptroller under that subsection, and (b) as a result of the observations, the comptroller is satisfied that the formal requirements have been complied with.

15A.24

If an applicant has been notified at least once that a requirement designated as formal by r.25(1) has not been complied with, and no satisfactory response has been received within the period specified (see 15A.20), a report may be issued stating that unless the applicant submits observations or requests a hearing within one month the application will be refused under s.15A(7). If no satisfactory response is received within this period, or if, following a hearing, the matter is decided against the applicant, a decision should be issued formally refusing the application.

The power to refuse must be exercised reasonably, and where applications are reasonably suitable for publication the comptroller may not exercise its power to refuse under s.15A(7), and allow the application to proceed instead. In such circumstances the applicant will be notified of the outstanding deficiencies but advised that the application will proceed to publication.

[ If the period specified in the preliminary examination report has elapsed without a satisfactory reply having been received, a letter drafted in some such terms as the following should be issued:-

The ……………….. requested by ……………….. have not been filed. The Comptroller will refuse your patent application unless by ……………….. (i) you file the requested ……………….. with a full explanation why they were not filed on time; or (ii) you make observations; or (iii) you request the opportunity to present your case, in person if you choose, to a senior official at the Office.

Care must be taken when preparing the letter, using the above as a base, to ensure that the correct requirement is inserted. The official letter must be authorised by the Formalities Manager. Where the formal requirement remains outstanding after expiry of the period specified in the Official Letter issued as above, the application is refused. Where the refusal is undisputed, a decision of refusal should be prepared and submitted through the Formalities Manager to the Examination Support Operations Manager for approval and signature. Cases where refusal is disputed should be submitted through the Formalities Manager and Examination Support Operations Manager to the appropriate Senior Legal Adviser in Legal Section for a hearing.

If the comptroller does not exercise his power to refuse the application, the applicant will be issued a final notice of the deficiencies identified but notified that the application will proceed to publication nevertheless. The letter will notify the applicant that, should they wish to prevent publication, the application must be withdrawn before the application is prepared for publication. To ensure that publication is prevented, it should be withdrawn no later than the day before the 18-month anniversary of the earliest date. ]

Section 15A(9)

If a report is made to the comptroller under subsection (3) above- (a) that any requirement of section 13(2) or 15(10) above has not been complied with; or (b) that a drawing or part of the invention has been found to be missing, then the comptroller shall notify the applicant accordingly.

15A.25

r.10(3), r.22(7) are also available

Any requirements of section 13(2) or 15(10) which have not been complied with within the prescribed periods (as extendible under r.108(2)) will be reported to the applicant in warning letter WR4 informing that the application has been taken to be withdrawn. The formalities manager should issue the letter at the appropriate time.

15A.26

Failure to respond to any finding under s.15A(4) that a part of the application appeared to be missing at the time of filing will result in a letter being issued by the formalities manager stating that the missing part has not been filed and that the application will proceed in the form that it was originally filed.