Say the prototype finally works. A trade fair slot is booked for the autumn and an investor wants a technical walkthrough next week. “When should I apply for a patent?” is a timing problem with a trap on each side. File too late and you can destroy your own invention’s novelty before an application reaches the UK Intellectual Property Office (UKIPO). File too early and you start a 20-year clock and fix your description before the invention has settled down. Most of the skill is steering between the two.
Filing too late
UK patent law requires absolute novelty. Under section 2 of the Patents Act 1977, an invention is new only if it has not been made available to the public before the application’s filing date, anywhere in the world, in writing, by word of mouth, by use or in any other way. The test does not care who did the disclosing. Your own launch video counts. So do a conference paper, a crowdfunding page, a trade fair stand and an unguarded pitch. Inventors do lose patents to their own marketing.
There is no general grace period in the UK. Section 2(4) disregards a few disclosures made in the six months before filing, chiefly information taken from you unlawfully or in breach of confidence, plus display at an “international exhibition”, declared when you file. None of this rescues an ordinary launch. The United States gives inventors a one-year grace period for their own disclosures while the UK gives none, so a disclosure that is survivable in a US filing can sink a British one.
A genuinely confidential disclosure is different. A demonstration under a signed non-disclosure agreement (NDA) has not been made available to the public, which is why NDAs usually come before detailed technical conversations. Waiting has a second risk. The UK is a first-to-file system: between rivals with the same invention, the earlier application wins, whoever invented first.
Filing too early
The opposite trap is quieter. A patent’s 20-year term runs from the day you file, however far off grant or launch may be, so an application filed three years before there is anything to sell spends three years of its life on development. The application is also published around 18 months after its earliest filing date. From then on any competitor can read your technical description, and it defeats any later attempt of your own to patent the same idea.
An application freezes the invention as described on filing day. If the design pivots six months later, the claims, the wording that defines what is protected, may cover the version you abandoned; improvements made after filing need a fresh filing with a later date. Nor does spending stop at grant: renewal fees fall due yearly from the fourth anniversary of filing and, as at July 2026, run from £90 for year 5 to £810 for year 20.
The priority year
The standard way out of the squeeze is the priority year. It begins with a first application, filed once the invention is stable enough to describe fully. Under section 5 of the Patents Act 1977, implementing the Paris Convention, applications filed within the next 12 months, in the UK or abroad, can claim the date of that first filing for everything it disclosed. The first filing freezes your position. A launch the following week no longer threatens the novelty of what it described.
Businesses commonly spend the year testing the market, raising money and refining the design, then file again before the deadline with improvements added: the original material keeps its original date; anything new takes the later one. Foreign decisions can wait until late in the year, once early sales suggest which markets matter. A single international application under the Patent Cooperation Treaty keeps the door open in over 150 countries and defers the expensive national stage by up to 30 months (31 in some countries) from the first filing.
Pitches, demos and investors
Investor conversations sit awkwardly here as they tend to happen before any filing, and an NDA is not always on offer. A common approach is to pitch what the product does and for whom, and keep how it works out of the deck. The “how” is usually where the patentable material lives. Where a technical deep-dive cannot be avoided, confidentiality terms go in first. And where a public date is immovable a demo day, a trade fair, a launch many businesses file beforehand. Even an application filed days before the event secures a date for what it describes. A dated record of who was shown what, and under which agreement, is cheap insurance.
What it costs, and how long it takes
Official fees are smaller than most people expect. After the 1 April 2026 fee rise, an online UK application costs £75 to file, £200 for the search and £130 for substantive examination (the examiner’s full check): £405 to grant for a straightforward case within 25 claims and 35 pages. Professional drafting, if you use a patent attorney, comes on top.
The timetable is the slower part. Search comes first, then publication at around 18 months, then examination. The IPO’s own guidance says the process can take several years; three to four and a half is a common estimate for an unaccelerated application. Acceleration is free. Combined search and examination usually produces both reports within about six months, accelerated handling can be requested with reasons, and the Green Channel does the same for inventions with an environmental benefit.
When the answer is not to patent
Sometimes the right filing date is never. A patent is a bargain with the state: up to 20 years of exclusivity in exchange for publishing how the invention works. If your advantage is a process nobody could reverse-engineer from the finished product, secrecy may protect it for longer, with no fees and no expiry date, whereas a patent application hands the method to every competitor once it is published at 18 months. Fast-moving products raise the same doubt from the other direction, where the sales window is shorter than the wait for grant, the sums rarely work. For how a patent fits into a wider budget, see our guide on building an IP portfolio on a startup budget.
A working rule of thumb
Stripped of detail, the rule is short. Most businesses file once the invention is stable enough to describe completely, and before anyone outside a duty of confidence has seen how it works; the priority year then absorbs the rest, from launch and roadshow to improvements and foreign filings. And if AI tools helped devise the invention, inventorship has rules of its own; our guide on patenting AI-assisted inventions covers where the line sits.
If a launch date or a funding round is bearing down on an unfiled invention, ScalaxIP can help you work out what to file and when. Get in touch.
Disclaimer: This article is provided for general information only and does not constitute legal advice. For advice on your specific circumstances, please contact ScalaxIP at admin@scalaxip.com
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