Common problems in patent applications

This webpage provides helpful information to avoid common errors when filing your nonprovisional utility patent application. Some of the most common problems in patent applications involve the topics below. 

Signatures

Documents requiring your signature may be filed with a handwritten (“wet ink”) signature or "S-signature" (electronic) signature, which are two types of approved signatures. Documents may also be signed by an electronic signature such as DocuSign® and Acrobat® Sign. Regardless, make sure documents are properly signed before filing them. The S-signature must only contain letters and Arabic numerals, with appropriate spaces and commas, periods, apostrophes, or hyphens for punctuation. You must insert your own S-signature; the S-signature is required to be between forward slash marks and separately include your name, normally underneath the S-signature. For example:

/Dr. James T. Jones Jr./

Dr. James T. Jones, Jr.

Retain in your records any original documents you and any other named inventors may sign. Both the printed name and the signature should be consistent among all documents for all signers. For joint inventors identified as co-applicants all of whom are domiciled in the United States, if the joint inventors are not represented by a registered practitioner, all joint inventors must sign all papers such as amendments and Application Data Sheets (ADS) submitted to the USPTO. Effective July 20, 2026, if at least one joint inventor co-applicant has a domicile that is not located within the U.S. or one of its territories, the joint inventor applicants must be represented by a registered practitioner. See 91 Fed. Reg. 13510 (March 20, 2026).

See our Signature examples document for additional guidance regarding signatures.

Micro Entity Certification Form

An application may qualify for micro entity status provided each inventor, applicant, and any other party with an ownership interest meets certain requirements. One or more application-specific micro entity certification forms must be filed in an application in order for fees to be paid in the application at the 80% micro entity discount. This video provides guidance in filling out the form. To help determine whether micro entity status is available for a particular application, please see information on micro entity status. What follows is more guidance about filling out the micro entity certification form for qualifying applicants. 

Signature — Only a USPTO-registered practitioner or a U.S.-domiciled applicant may sign the form. Joint applicants should sign separate copies of the form. If the applicant is a juristic entity (e.g., a corporation), a USPTO-registered patent attorney or agent must sign the form. See also Who May Sign.

When U.S.-domiciled joint inventors identified as the applicant are each signing a separate copy of the certification form, each joint inventor should check the box at the very bottom left of the signature block indicating that separately signed forms from the other joint inventors are included.

Identifying information — The top of the form includes boxes for identifying the application by its number, the first named inventor, and the title of the invention, as shown below:

Application Number or Control Number (if applicable):
 		Patent Number (if applicable):
 
First Named Inventor:
 		Title of Invention:
 

Application Number and Patent Number boxes – Micro entity certifications are often included with a new application filing, in which case there will not be an application number to enter in the “Application Number or Control Number” box. Therefore, when micro entity certifications accompany a new application filing, both the “Application Number or Control Number” and “Patent Number” boxes must be left blank. For micro entity certification forms filed before an application number is assigned, the application must be identified with both the first named inventor and the correct title of invention. A micro entity certification filed after the initial filing of the application should include the application number entered in the “Application Number or Control Number” box. The “Patent Number” box is left blank unless the application has gone through examination and a patent has issued, and micro entity status is to be established for purposes of paying discounted patent maintenance fees, for example.

First Named Inventor - The first named inventor is the full name of the first inventor listed in the “Inventor Information” section of the Application Data Sheet (ADS). If U.S.-domiciled joint inventors are the applicant (e.g., when there is no assignee-applicant), and all joint inventors are signing separate micro entity certification forms, the name entered in the “First named inventor” block should be the same for all the micro entity certification forms separately signed by each joint inventor.

Title of Invention - The title listed must match the title listed on the ADS or the title placed at the top of the first page of the application specification (learn more about common ADS mistakes below). If the certification of micro entity status does not properly identify the application, a notice will be mailed and a fee assessed.

All application-identifying information on the form must be consistent with the application in which it is filed. The USPTO gives every application, whether provisional or nonprovisional, a unique identifier. If you previously filed a provisional application and then file a nonprovisional application covering the same subject matter, the nonprovisional will be assigned its own number.

Application Data Sheet (ADS)

An ADS is a form that lists information about the applicant, all named inventors, and how to correspond with them, as well as details about the application itself along with (where applicable) domestic benefit, foreign priority, and assignees. You must submit an ADS if you wish to claim the benefit of an earlier filed application or name an applicant in the applicant section of the ADS. Because many pro se applicants (those applying without an attorney or registered agent) often first file a provisional application, the ADS is necessary when eventually filing the nonprovisional application.

The webpages Tips for Application Data Sheets and Important information for completing an Application Data Sheet (ADS) cover details not found here.

Every ADS must be signed in accordance with 37 CFR 1.33(b) either by a USPTO-registered patent practitioner (attorney or agent) or you the inventor-applicant if you are domiciled in the U.S. When a name in the Applicant Information section is what’s called a “juristic entity” (for example, a company you own), the ADS must be signed by such a practitioner. Juristic entity applicants and foreign-domiciled applicants must have a USPTO-registered practitioner sign the ADS as well as other papers including replies, amendments, micro entity certifications, information disclosure statements, petitions, and other correspondence received in patent matters. An unsigned ADS will be treated only as a transmittal letter adding limited information to the official application record.

If you wish to claim the benefit of an earlier-filed application, including a provisional, the claim must be made in the “Domestic Benefit/National Stage Information” section of an ADS. Take extra care to complete the correct information for each box, and we strongly encourage reading the detailed instructions before filling out the ADS.

Filing by Reference section — In most circumstances, it should be left blank, because it relates to laws that don’t apply to most applicants. This section is unrelated to claiming the benefit of an earlier application, and mistakenly completing it can be costly and time-consuming.  This section is for the extremely rare situation where the application filing includes no disclosure of the invention by way of a specification and any drawings, and the applicant is relying instead on later submitting a copy of a previously filed application referenced in this section.

Showing changes to the record — Anytime an ADS is filed after initial filing of the application, whether the first submission or a correction, the ADS must identify the information being changed relative to the information of record. You must identify these changes by underlining insertions, with strikethroughs (strikethrough) or double brackets ([[double brackets]]) for removals. When an ADS was not submitted during the initial filing, all text being added must be underlined. If an ADS was submitted on filing but some of the information was not picked up due to some error, then that information is not of record and the text must be underlined.

Typographical errors — Carefully check each entry in the ADS for typos. Errors in the spelling of names, application numbers, and addresses, to name common examples, can be hard to fix and can cost you money, time, and additional paperwork.

By being aware of these common mistakes, carefully reading the entire form, and proofreading for typos, you can avoid the unnecessary time and expense that comes from correcting mistakes on USPTO forms.

Proper formatting for specifications

Every nonprovisional utility application is required to have a specification, including a written description of the invention and at least one claim. Oftentimes, applicants, including pro se applicants (those not represented by a registered patent attorney or agent) do not properly format the specification or leave out required sections. This may lead to the Office of Patent Application Processing (OPAP) sending a notice requiring correction of deficiencies.

The USPTO provides a DOCX Initial Filing Template to assist applicants with formatting new utility applications in DOCX format. This is a simplified template for new filings with the most common specification sections. In Patent Center, this template will autodetect the Specification, Claims, Abstract, and Drawings sections.

Specification pages, including the abstract and claims, must meet the following general formatting requirements:

  • Provided in English with 1.5-inch or double-spaced lines in a single column of text
  • Written on only one side in portrait orientation
  • Sheets must be 8.5 x 11 inches, with all margins at least ¾ inches except the left margin (must be at least 1 inch)
  • Clearly typewritten in a non-script font (common examples include Arial, Times New Roman, and Courier), preferably 12-point and without shading, on white paper
  • Application pages numbered consecutively (centrally located above or below the text) starting with Page 1 (just the numeral — without “Page”)
  • Drawing figures must not be contained within the specification

The Nonprovisional (utility) patent application filing guide provides guidance on the content and arrangement of a utility application specification. As discussed, a specification requires a title of the invention. Although the title may have up to 500 characters, the title must be as short and specific as possible. The title should appear as a heading at the top of the first page of the specification.

The most common applicable sections that should follow the title are:

The claims (refer to the Assistance with claim drafting presentation for more direction) and the abstract (one paragraph, less than 150 words, must each begin on a separate sheet.

The specification should be as detailed as possible but still be sufficiently clear, full, concise, and exact to satisfy the written description, enablement, and best mode requirements. For more information on drafting a specification, see section 608.01 of the Manual of Patent Examining Procedure (MPEP).

You cannot add to your application any subject matter that is not supported by the specification, claims, or drawings that were present on the filing date. Subject matter not present on the filing date is usually considered “new matter” and will not be entered into the disclosure. For more guidance on new matter, see section 608.04 of the MPEP.

What are claims? 

Your claims are the heart of your patent application — they set the scope of exactly what the patent covers (and doesn’t cover). If a patent is granted, the claims define what the patent owner has the right to exclude others from making, using, selling, or importing into the United States (only those things described by the claims).

Prosecution may be more efficient if you include claims varying from the broadest you believe you’re entitled to, down to the most detailed you’re willing to accept. Arrange your claims in order of scope so that your first claim is the least restrictive. Whenever practical, all dependent claims should be grouped together with the claim or claims to which they refer.

Online filing

A USPTO.gov account can save you time and effort when filing a patent application while protecting your information. If you’re a “pro se” applicant, meaning you’re applying for a patent without a practitioner (i.e., USPTO-registered attorney or agent), please be aware that you must register for a USPTO.gov account to file online through Patent Center. This will improve your experience filing your application and follow-on papers. Note that, beginning July 20, 2026, applicants and patent owners whose domicile is not located within the U.S. or its territories must be represented by a USPTO-registered patent practitioner.

Once all your documents are ready, submit your application in Patent Center through your validated USPTO.gov account. Filing online provides a better guided filing experience and avoids additional paper-filing fees. Here are some resources to help you:

You should file application-related documents through Patent Center in DOCX format. DOCX filing is available for the specification, claims, abstract, and drawings. Specifications, claims, and abstracts not filed in DOCX format will incur an additional surcharge. DOCX is key to helping the USPTO provide quick, reliable feedback so you can correct your application if needed and prevent unnecessary processing delays.

Determining correct fees

You can electronically submit the required filing, search, and examination fees using a credit card or electronic funds transfer. It is best to pay these fees online when filing the application rather than later, because any such fee paid after the application filing date requires an additional fee. All fees are subject to change, and additional fees may apply depending on the specifics of your application. Consult the current fee schedule before filing your application.

What is an OPAP notice and how do I reply?

Once we’ve received your application, the Office of Patent Application Processing (OPAP) will conduct a review (“pre-exam”) to ensure that your application is complete and meets certain requirements. If your application contains informalities or is incomplete, you will receive a notice outlining the requirements to complete your application.

OPAP reviews filings to see if:

  • The application meets filing date requirements
  • The required information is provided
  • Certain forms are properly completed and signed
  • The language, paper, and other formatting is compliant with applicable rules
  • Fees are properly calculated and paid

An OPAP notice identifies what is incomplete or missing in your application, what you need to do to correct all issues, your deadline for a complete reply to the notice, and any additional fees required. Each notice may indicate more than one problem with your application, so read the notice carefully. More information about these notices can be found on the related When patent applications are incomplete or missing information webpage.

Common mistakes found during OPAP drawing review

Many drawing requirements apply when drafting a patent application. Here are some common issues with filed drawings:

  • Line quality too light to be reproduced
  • Submitting color drawings in a utility application without a grantable petition to accept color drawings, including the required petition fee
  • Stray marks on drawing sheets caused by photocopying
  • Missing lead lines (lines between the reference characters and the details referred to)
  • Excessive or non-English text
  • Paper formatting problems (examples include incorrect margins and improper paper size)
  • Non-permitted elements (examples include framing, scaling, dimension, keys, titles, and blocks)
  • Unnumbered or misnumbered multiple views
  • View numbers not preceded by the abbreviation "FIG." (for “Figure”) with a consecutive Arabic numeral (1, 2, etc.) or an Arabic numeral and capital letter in the English alphabet (1A, 1B, etc.)
  • Specification missing list of all figures by number with brief description of what the figure depicts, or each brief description not corresponding to a separately labeled drawing figure
  • Incorrectly labeled figures (reference characters in figures must be consistent with the specification)

How to amend drawings

Each drawing sheet submitted after the filing date of an application must be labeled in the top margin as either “Replacement Sheet” (if making changes to an already filed drawing sheet) or “New Sheet” (if including a new drawing sheet containing any additional new drawings). Even when better drawing quality is the only change to already filed drawings, each changed drawing sheet must be identified as a “Replacement Sheet.” An explanation of changes made must be presented in the “Amendments to the Drawings” or the “Remarks” section of the amendment document. When substantive changes are being made to the already filed drawings, the explanation of changes may include a marked-up copy corresponding to a replacement sheet(s) of drawings including annotations indicating the changes made. The marked-up copy must be clearly labeled as “Annotated Sheet” and must be presented in the amendment or remarks section that explains the change to the drawings. See MPEP section 714, subsection II.D for more information.

Filing a substitute specification

When responding to an OPAP notice requiring a substitute specification, or an examiner’s requirement for a substitute specification, your submission requires three parts (except in limited situations), each in separate documents:

  1. Marked-up copy — with proper markings showing all changes as compared to the most recent version of the specification of record (for example, if submitting a second substitute specification, the markings must show all changes as compared to the first substitute specification, not the original). Additions of text must be underlined. Deletions must be shown by strike-through, except that double brackets may be used if strike-through cannot be easily perceived, or when deleting five or fewer consecutive characters, as in [[this]]. Numbering the paragraphs of the specification is not considered a change that must be shown.
  2. Clean copy (without markings) — a version that includes all changes as compared to the most recent version of the specification of record. This version should not contain markings.
  3. A signed statement declaring “The substitute specification submitted under 37 CFR 1.125 includes no new matter” (37 CFR 1.125 is the rule that applies to substitute specifications).

The entire specification (minus the claims and abstract) is required for the marked-up and clean copies, not just the amended portion.

In limited situations, only a clean copy of the substitute specification is required (along with the signed statement that the substitute specification includes no new matter) and the notice will state this if that is the case. For example, this may be the case when the only amendment needed is to correct the line spacing in the specification.

Understanding Office actions and how to reply

Once your application has been assigned for examination, your examiner will review its contents to determine if it meets all requirements for patentability. You will be notified in writing of the examiner’s decision – this is called an “Office action.” If the examiner determines that the application does not meet all of the requirements for patentability, the reasons for the determination will be explained. The examiner may, and often does, reject claims in an application on the basis of prior patents or publications (prior art).

You can either amend your application or argue against the examiner's decision, normally at no cost if you meet the deadline noted in the examiner's Office action. If amending your application in reply to an Office action, you must clearly point out why you think any amendments made cause the claims to be patentable by overcoming rejections or objections made by the examiner. If arguing in your reply to an Office action, you must clearly point out why you think that the rejections or objections made by the examiner are wrong.

Failure to respond to the examiner's Office action within the required period for reply set forth in the Office action (and any applicable extensions of time) will lead to your application being abandoned. Here are some resources to help you better respond to Office actions:

How do I amend my claims?

You can amend your claim or claims in response to the examiner’s Office action, by including a claim listing section in your response. The claim listing section must begin on a separate sheet, must include a complete listing of all claims ever presented in the application, and should be entitled “Amendments to the Claims.”

There are several key requirements for the claim listing section:

  1. Claim Numbering: All of the claims must be presented in ascending numerical order (starting with 1) and be numbered consecutively. You must maintain the original claim numbering throughout prosecution. Do not renumber claims. If you add a new claim, use the next number following the highest numbered claim that was previously presented (for example, for an application originally having 10 claims, the first new claim you add would be numbered as Claim 11).
  2. Status Identifiers: You must provide the current status of every claim in the application, including any previously canceled or withdrawn claims, by providing a status identifier in a parenthetical following the claim number. Use only the following status identifiers: (original), (currently amended), (previously presented), (canceled), (withdrawn), (withdrawn – currently amended), (new), or (not entered).

  3. Claim Text: You must address every claim in the claim listing section, even if you are only amending one claim. The way in which you address the claim will vary depending on its status:

    a. If the status identifier is (original), (previously presented), (withdrawn), or (new), then present the claim text in a clean version without any markings.

    b. If the status identifier is (currently amended) or (withdrawn – currently amended), then present the claim text with markings to show the changes, as explained below in point 4.

    c. If the status identifier is (canceled) or (not entered), then present only the claim number and the status identifier. Do not include the text of the claim.

  4. Markings to Show the Changes: All claims that you are currently amending must be presented with markings to show the changes that have been made relative to the immediate prior version. Added matter must be underlined. Deletions must be shown by strike-through, except that double brackets may be used if strike-through cannot be easily perceived, or when deleting five or fewer consecutive characters, as in [[this]]. Do not provide a clean version of an amended claim. If you are amending a claim, its status identifier should be either (currently amended) or (withdrawn – currently amended).

The requirements for making claim amendments in a reissue application or a reexamination proceeding are more complex, and you may wish to consult a registered patent attorney or agent if you have questions.

How long do I have to reply?

Be careful not to delay your reply to USPTO communications. USPTO communications set a period for reply – typically two or three months. If necessary, in most instances, you can apply for an extension of the period for reply by filing a petition, accompanied by the appropriate fee. (Note that replies to Office actions cannot be extended beyond six months of the mailing date of the Office action). The date on which the reply is filed will determine the extension time period and the corresponding fee due, if any. Additionally, not submitting a timely, acceptable response to an Office action will result in your application being “abandoned” (removed from the Office docket of pending applications).

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