A non-provisional patent application has a fixed structure and one rule that governs everything: nothing can be added after filing. What follows is a non-provisional patent application example running through every section.
The claims define what you own. They can be amended during prosecution, but only within what the description already discloses.
Which makes the detailed description the ceiling. A variation not written on day one is permanently unavailable, however obviously it belongs.
Everything below is that structure, with a worked example running through it.
The required sections
| Section | Purpose |
|---|---|
| Title | Short, descriptive |
| Cross-reference to related applications | Priority claims |
| Background | The problem |
| Summary | The invention in brief |
| Brief description of the drawings | One line per figure |
| Detailed description | Enables the invention; supports the claims |
| Claims | What you own |
| Abstract | 150 words or fewer |
| Also filed | Purpose |
|---|---|
| Drawings | Where necessary to understand |
| Application Data Sheet | Bibliographic data, priority |
| Declaration | Inventor statements |
| Information Disclosure Statement | Duty of candour |
| Fees | Filing, search, examination |
| Assignment | Where rights are held by an entity |
The example
A device that reduces sediment carryover in a fluid line by staging the flow.
Everything below tracks this one invention through the sections.
Title and cross-references
Title: Staged flow separator with variable-aperture baffle
Cross-reference: This application claims priority to US Provisional Application No. 63/XXX,XXX, filed 14 March 2025.
Keep the title descriptive and unrevealing. It publishes, and a title naming your commercial product connects the two permanently.
The cross-reference carries the priority claim. Priority extends only as far as the provisional actually enabled, so a thin provisional supports less than its date suggests. See provisional patent application.
Background
Fluid transfer lines carrying suspended solids experience sediment carryover when flow velocity varies. Existing separators use fixed-aperture baffles, which perform adequately at design velocity and lose efficiency outside it...
| Do | Do not |
|---|---|
| Describe the technical problem | Describe a market opportunity |
| Explain why existing approaches fall short technically | Disparage specific competitors |
| Keep it brief | Characterise prior art broadly |
| Stay factual | Admit anything is prior art unnecessarily |
Statements here can be used against you. Characterising something as well known in the art may be treated as an admission.
A background framing a market problem signals a business method, which matters enormously for software and service inventions. See what can be patented.
Summary
A separator is disclosed comprising a housing defining a flow path, a baffle disposed within the flow path and having an aperture, and a biasing element coupled to the baffle such that aperture area varies with flow velocity...
Track the independent claims. The summary should state the invention at approximately the breadth the broadest claim recites.
Include the advantages, briefly. They support arguments about unexpected results later.
Brief description of the drawings
FIG. 1 is a perspective view of a separator according to one embodiment. FIG. 2 is a cross-sectional view taken along line 2-2 of FIG. 1. FIG. 3 is a detail view of the biasing element of FIG. 2. FIG. 4 is a cross-sectional view of an alternative embodiment...
One line per figure, in order. This section is mechanical and errors in it draw objections.
Detailed description: the section that matters
| Requirement | What it means |
|---|---|
| Enablement | A skilled person could make and use it |
| Written description | You possessed what you claim |
| Best mode | The best way you knew at filing |
| Support for every claim term | Each term traceable to the description |
| Alternatives described | The only way to preserve amendment room |
Describe alternatives generously. Materials, ranges, geometries, arrangements — each described alternative is a fallback position during prosecution.
Ranges matter. "Approximately 15 degrees" supports narrower amendment than "from about 5 to about 40 degrees, preferably 12 to 18 degrees, most preferably about 15 degrees."
Reference numerals must be consistent between text and drawings throughout.
From the example
The biasing element 30 may comprise a helical spring, a leaf spring, an elastomeric member, or a magnetic assembly. In the embodiment of FIG. 2, biasing element 30 is a helical spring having a spring constant of from about 2 N/mm to about 20 N/mm, preferably from about 6 N/mm to about 10 N/mm...
Four alternatives for the biasing element, and a range with preferred sub-ranges.
Each one is amendment room. If prior art discloses a spring-biased baffle, the magnetic embodiment is available — but only because it was written down.
Claims
| Type | Function |
|---|---|
| Independent | Stands alone; broadest coverage |
| Dependent | Adds a limitation to an earlier claim |
| Apparatus | Reaches makers, sellers, importers |
| Method | Reaches whoever performs the steps |
| System | Combinations |
Independent apparatus claim
1. A flow separator comprising: a housing defining a flow path having an inlet and an outlet; a baffle disposed within the flow path, the baffle defining an aperture; and a biasing element coupled to the baffle and configured to vary an area of the aperture in response to a flow velocity within the flow path.
Dependent claims
2. The separator of claim 1, wherein the biasing element comprises a helical spring. 3. The separator of claim 2, wherein the helical spring has a spring constant of from about 6 N/mm to about 10 N/mm. 4. The separator of claim 1, wherein the biasing element comprises a magnetic assembly.
Independent method claim
9. A method of separating suspended solids from a fluid stream, comprising: directing the fluid stream through a flow path; varying an aperture area of a baffle disposed in the flow path in response to a flow velocity...
Note the transition word. "Comprising" is open, so a product containing everything recited plus more still infringes. "Consisting of" is closed and rarely what you want.
Claim 4 is why the alternatives mattered. If a spring is anticipated, claim 4 survives — and it exists only because the magnetic assembly appeared in the description.
Method claims reach different parties, which matters where a device is made by one company and operated by another.
Claim structure strategy
| Level | Purpose |
|---|---|
| Broadest independent | Maximum coverage; most likely to be rejected |
| Middle independent | Fallback with one added limitation |
| Narrow independent | Likely to survive; covers your product |
| Dependents on each | Amendment room without new claims |
Write at several levels deliberately. An application with one broad independent claim and nineteen dependents has one position; losing it means amending under pressure.
The narrowest independent should cover your own product with room to spare, since that is the claim you most need to survive.
Dependents are cheap fallbacks. Each one is a pre-drafted amendment that requires no new support argument.
Claim fee thresholds
| Included | Excess fee applies | |
|---|---|---|
| Total claims | 20 | Beyond 20 |
| Independent claims | 3 | Beyond 3 |
| Multiple dependent claims | 0 | Any, and expensive |
Most applications are structured to fit 20 and 3. Exceeding it is a deliberate decision, not an accident.
Multiple dependent claims carry a substantial surcharge and are uncommon in US practice.
Prosecution reshapes the claims
| Event | Effect |
|---|---|
| §102 rejection | Prior art discloses everything claimed |
| §103 rejection | Most common — obvious combination |
| §112 rejection | Support, clarity or enablement |
| §101 rejection | Eligible subject matter |
| Amendment to overcome art | Surrenders scope permanently |
| Argument without amendment | Preserves scope, may not succeed |
Amendments create prosecution history estoppel, barring equivalents in the surrendered range. Arguing without amending preserves more, and does not always work.
Every response is a permanent decision about what the patent will cover. See prosecution history estoppel.
Abstract
A flow separator includes a housing defining a flow path, a baffle within the flow path defining an aperture, and a biasing element that varies the aperture area in response to flow velocity, reducing sediment carryover across a range of operating conditions.
150 words or fewer, one paragraph, no legal phrasing.
It is a search tool, not a legal document. Claims are not construed by reference to the abstract.
Drawings
| Requirement | Detail |
|---|---|
| Show every claimed feature | A claim term with no figure support draws objections |
| Reference numerals | Consistent throughout |
| Line quality | Black ink, defined standards |
| Views | As many as needed for understanding |
| Shading and hatching | Per convention |
Features shown but never described create problems. Every numbered element should appear in the detailed description.
Informal drawings can be filed and replaced with formal ones later, which is common practice. See patent drawing.
The forms
| Form | Purpose |
|---|---|
| Application Data Sheet | Inventors, priority, correspondence |
| Declaration | Each inventor's statements |
| IDS | Prior art known to the applicant |
| Fee transmittal | Payment |
| Assignment | Where an entity holds rights |
| Micro or small entity certification | Reduced fees |
The IDS carries a duty of candour. Failure to disclose material prior art known to you can render a patent unenforceable, which is a far worse outcome than a rejection.
Supplement it. Art found after filing, including in foreign counterparts, should be submitted as it becomes known.
Filing routes
| Route | Use |
|---|---|
| Direct US non-provisional | US only, term starts now |
| From a provisional | Within 12 months, claims that priority |
| PCT then US national stage | Defers the foreign decision to ~30 months |
| Continuation | Further claims from a pending parent |
| Divisional | Where a restriction requirement was issued |
A restriction requirement is common where an application claims what the examiner considers distinct inventions. The non-elected claims go into a divisional, which keeps them alive.
Track restriction requirements. Failing to file the divisional before the parent issues abandons those claims permanently.
The costs
| Item | Large | Small (40%) | Micro (20%) |
|---|---|---|---|
| Filing, search, examination | ~$2,000 | ~$800 | ~$400 |
| Drafting (attorney or agent) | $5,000–$15,000 | Same | Same |
| Office action responses | $2,400–$8,000 | Same | Same |
| Issue fee | ~$1,200 | ~$480 | ~$240 |
| Maintenance fees, lifetime | $14,470 | $5,788 | $2,894 |
Drafting is the largest cost and the one not to cut. Official fees scale with entity status; professional fees do not.
A patent agent charges less than an attorney for the same registration and the same drafting work. See patent attorneys.
Inventorship must be right
| Rule | Detail |
|---|---|
| Inventors are those who conceived the claimed invention | Not who funded or managed it |
| Contribution to at least one claim | Sufficient |
| Following instructions | Not inventorship |
| Errors | Correctable, but deliberate misnaming can invalidate |
| Joint inventors | Each may license the whole invention absent agreement |
Inventorship changes when claims change. An amendment removing the claims one contributor conceived may remove them as an inventor, and the correction should be made rather than left.
Naming a manager as a courtesy is a real risk. See inventorship.
After filing
| Event | Timing |
|---|---|
| Filing receipt | Weeks |
| Publication | 18 months from earliest priority |
| First office action | 19.9 months average, FY2024 |
| Response | 3 months, extendable to 6 |
| Disposal | 26.3 months average, FY2024 |
| Continuation decision | At notice of allowance — no reminder |
| Issue fee | 3 months, no extension |
The continuation window is the most commonly missed decision. Once the parent issues with nothing pending, the family is closed permanently.
Term runs from this filing date, not from the provisional. See patent application process.
What the description must carry forward
| If prior art appears against | You need in the description |
|---|---|
| The spring | The magnetic alternative |
| The 15-degree angle | A range with sub-ranges |
| The material | Alternative materials named |
| The arrangement | Alternative geometries |
| The whole combination | A narrower embodiment |
Every row is amendment room that exists or does not. None can be created after filing.
This is why drafting cost is not the place to save. A cheap application that issues with claims any competitor designs around in an afternoon spent the fees for nothing.
The mistakes that cost most
| Mistake | Consequence |
|---|---|
| Too few alternatives described | No amendment room when art appears |
| Narrow ranges only | Cannot retreat to a sub-range |
| Claims mirroring one embodiment | Trivially designed around |
| Background admitting prior art | Used against you |
| Missing IDS disclosures | Unenforceability |
| Inconsistent reference numerals | Objections and delay |
| Claim terms unsupported in the description | §112 rejections |
| Filing after public disclosure | Rights forfeited in most countries |
The first is the expensive one. Every prosecution problem is easier when alternatives exist in the description, and none of them can be fixed afterwards.
Non-provisional patent application: the checklist
- Nothing can be added after filing. Write the alternatives in now.
- Describe ranges with preferred sub-ranges, not single values.
- Frame the background as a technical problem, never a market one.
- Avoid admitting anything is prior art unnecessarily.
- Make the summary track the independent claims.
- Support every claim term in the detailed description and the drawings.
- Use "comprising" unless there is a specific reason not to.
- Include both apparatus and method claims where both apply.
- Structure around 20 total and 3 independent claims unless exceeding is deliberate.
- File the IDS and supplement it. The duty of candour outlasts filing.