PCT Patent Filing Process Explained

PCT Patent Filing Process Explained | Generated by AI

Home 2026.07

Question: Introduction to the Patent Cooperation Treaty (PCT)

Answer:

Patent Cooperation Treaty (PCT) is an international patent filing system that allows an inventor or company to seek patent protection in many countries through one initial international application, instead of filing separate patent applications in each country immediately.

It is administered by World Intellectual Property Organization (WIPO) and entered into force in 1978.

Why PCT exists

Before PCT, if you invented something and wanted protection in:

US
Japan
Europe
China
Korea

you generally had to prepare and file separate patent applications in each jurisdiction.

Problems:

expensive translation costs
different filing rules
many legal deadlines
hard to decide early which countries are worth entering

PCT creates a single international pipeline.

Basic PCT workflow

Inventor
   |
   | 1. File PCT application
   v
Receiving Office
   |
   | 2. International Search
   v
International Searching Authority
   |
   | 3. Search Report + Written Opinion
   v
International Publication (~18 months)
   |
   | 4. Optional International Preliminary Examination
   v
National Phase Entry
   |
   +--> US Patent Office
   +--> European Patent Office
   +--> China Patent Office
   +--> Japan Patent Office
   +--> etc.

Important:

PCT does NOT grant an international patent.

There is no such thing as a “world patent”.

The final decision is still made by each country’s patent office.

Timeline

Typical timeline:

Month 0

File priority patent application.

Example:

Jan 1, 2026
US provisional patent filed

Month 12

File PCT application claiming priority.

Jan 1, 2027
PCT filed

Month 18

PCT application published publicly.

July 2027
Publication

Month 30/31

Enter national phase.

Example:

July 2028
US national phase
China national phase
Europe national phase

You get roughly 30 months to decide where you really want patents.

Example: Mango refrigerator idea

Suppose you invent:

A refrigerator that detects mango ripeness using optical sensors and automatically starts cooling.

You file:

PCT application:
"System and method for autonomous fruit ripeness control"

During the next 30 months:

You can evaluate:

Is the technology valuable?
Are companies interested?
Which markets matter?

Then choose:

US
China
Japan
Europe
India

and only pay expensive national fees there.

What happens during international search?

A patent examiner searches existing knowledge:

patents
academic papers
technical documents

They produce:

International Search Report (ISR)

Usually:

A = relevant but not destroying novelty
X = especially relevant, may destroy novelty
Y = relevant combination

Example:

Claim:
"Use infrared spectrum + humidity + temperature
to predict mango ripeness"

Prior art:
A paper from 2018 already uses infrared spectrum.

Result:
Claim may need narrowing.

PCT advantages

1. Delay cost

Instead of immediately paying:

10 countries × patent fees

you pay:

1 PCT filing

then decide later.

2. Better investment signal

For startups:

A PCT application can show:

technical seriousness
international ambition
IP strategy

Investors often like seeing patents, although patents alone do not guarantee business value.

3. Unified search feedback

You get early feedback:

“Your invention may not be novel.”

before spending money worldwide.

Limitations

No automatic patent

A PCT application is only a filing route.

Final approval:

USPTO decides US patent
CNIPA decides Chinese patent
EPO decides European patent

Expensive later

Entering many countries can become very expensive.

Example:

PCT filing:
~ several thousand USD

National phase:
US + Europe + China + Japan
could become tens of thousands USD

Software patents are complicated

For AI/software inventions:

The patentability depends heavily on jurisdiction.

Example:

"Use GPT to summarize text"

probably weak.

But:

"A specific neural architecture,
training optimization,
hardware acceleration method,
or technical control system"

may be stronger.

PCT vs normal patent filing

	Normal filing	PCT
Countries	One country	Many possible countries
Initial cost	Lower	Higher
Decision time	Short	~30 months
International search	No	Yes
Gives patent directly	Yes (if granted)	No

For a hardware + AI product like the mango refrigerator concept, PCT is often the route a startup would consider after the invention has enough commercial potential:

Prototype
   ↓
File provisional/local patent
   ↓
Test market
   ↓
PCT filing
   ↓
Choose countries
   ↓
National patents

The key idea: PCT buys time and preserves options. It is an international patent application strategy, not an international patent itself.

References:

Back Donate