MPEP 1875.01
Preparation of Invitation Concerning Unity

Ninth Edition of the MPEP, Revision 07.2022, Last Revised in February 2023

Previous: §1875 | Next: §1875.02

1875.01    Preparation of Invitation Concerning Unity [R-07.2015]

The "Invitation to restrict or pay additional fees," Form PCT/IPEA/405, is used to invite the applicant, at his/her option, to restrict the claims to comply with the requirements of unity of invention or to pay additional examination fees. In addition, the examiner must explain the reasons why the international application is not considered to comply with the requirement of unity of invention. The examiner must also specify, on Form PCT/IPEA/405, at least one group or groups of claims which, if elected, would comply with the requirement for unity of invention.


In the space provided on form PCT/IPEA/405, the examiner should identify the disclosed inventions by claim numerals and indicate which disclosed inventions are so linked as to form a single general inventive concept, thereby complying with the requirement of unity of invention. For example, claims to different categories of invention such as a product, claims to a process specifically adapted for the manufacture of the product and a claim for a use of the product would be considered related inventions which comply with the unity of invention requirement, whereas a claim to an apparatus for making the product in the same application would be considered a second invention for which additional fees would be required. The reasons for holding that unity of invention is lacking must be specified. See 37 CFR 1.475 and Chapter 10 of the International Search and Preliminary Examination Guidelines which can be obtained from WIPO’s website ( ).

Also, the examiner should specify the main invention and claims directed thereto which will be examined if the applicant fails to restrict or pay additional fees. The main invention, in case of doubt, is the first claimed invention or related invention before the International Preliminary Examining Authority for which a search fee has been paid and an international search report has been prepared.

The examiner should indicate the total amount of additional fees required for examination of all claimed inventions.

In the box provided at the top of the form, the time limit of one month for response is set according to PCT Rule 68.2. Extensions of time are not permitted.

Since the space provided on Form PCT/IPEA/405 is limited, supplemental attachment sheets, supplied by the examiner, with reference back to the specific section, should be incorporated whenever necessary.


Form PCT/IPEA/405 must be signed by an examiner with at least partial signatory authority.


Telephone practice may be used to allow applicants to elect an invention to be examined or to pay additional fees if:

  • (A) Applicant or applicant’s legal representative has a USPTO deposit account,
  • (B) Applicant or the legal representative or agent orally agrees to charge the additional fees to the account, and
  • (C) A complete record of the telephone conversation is included with the written opinion, if any, or the international preliminary examination report, including:
    • (1) Examiner’s name;
    • (2) Authorizing attorney’s name;
    • (3) Date of conversation;
    • (4) Invention elected and/or inventions for which additional fees paid; and
    • (5) Deposit account number and amount to be charged.

When the telephone practice is used in making lack of unity requirements, it is critical that the examiner orally inform applicant that there is no right to protest the holding of lack of unity of invention for any group of invention(s) for which no additional examination fee has been paid.

The examiner must further orally advise applicant that any protest to the holding of lack of unity or the amount of additional fee required must be filed in writing no later than one month from the mailing date of the written opinion or the international preliminary examination report if the lack of unity holding is first mailed with the IPER because there was no written opinion. The examiner should fill in the information on Form USPTO/499 "Chapter II PCT Telephone Memorandum for Lack of Unity" as a record of the telephonic holding of lack of unity.

If applicant refuses to either restrict the claims to one invention or authorize payment of additional fees, or if applicant does not have a deposit account, Form PCT/IPEA/405 should be prepared and mailed to applicant.

If a written invitation is required, the examiner should, if possible, submit that written invitation to the TC for review and mailing within 7 days from the date the international application is charged to the examiner.

See MPEP § 1850 for form paragraphs for lack of unity in international applications.