Paris convention

China IP Guides

By Peter Lin/ On 10 Dec, 2025

12 vs. 30 Months: Mastering the Critical Windows for China Patent Protection

Two numbers define your strategic window for China Patent protection: 12 months and 30 months. Get them confused, miss one of them, or misunderstand what they actually trigger — and you could lose rights that no amount of money can recover later. I've seen this happen. A founder assumes the 30-month PCT deadline applies to their situation, misses the 12-month Paris Convention window, and loses China priority. The patent can still be filed, but it now faces prior art that didn't exist when the clock started. Let me walk through both windows precisely. The 12-Month Window: Your Priority Clock Starts Here When you file your first patent application anywhere in the world — whether a US provisional, a UK complete application, or a Chinese utility model — a clock starts. Under the Paris Convention, you have 12 months from that first filing date to file in other member countries (including China) and claim priority back to that original date. What "claiming priority" means in practice: if you file in China within 12 months of your original filing, CNIPA will treat your application as if it was filed on the original date. Any competing applications or disclosures that appeared after your original filing date won't be counted as prior art against you. The 12-month deadline is absolute. There is no extension. If you miss it, you cannot claim Paris Convention priority for that filing. What happens at month 12 if you're going via PCT? Nothing special — as long as you file your PCT application before the 12-month Paris Convention deadline. Your PCT application, filed within 12 months of your original application, preserves your priority date and pushes your real China national phase decision out to month 30. This is the key insight: filing a PCT application within 12 months doesn't mean you're entering China at month 12. It means you're buying time until month 30 while protecting your priority date. The 30-Month Window: Your China Entry Deadline If you've gone the PCT route, month 30 from your original priority date is when you must enter the Chinese national phase. This means:Submitting your Chinese translation of the full application Paying China's official filing fees (calculated on claim count and page count) Formally committing to prosecution in ChinaMissing the 30-month deadline is also absolute for most countries. China does not provide a general grace period for late national phase entry. A missed deadline means you must re-file without priority — and everything that's been published in the intervening 30 months can be used against you. The Zone Between 12 and 30 Months: Use It Most inventors and even some IP teams treat this 18-month window as administrative dead time. That's a waste. Here's how to use months 12–30 productively: Refine your claim strategy. Use this time to assess the Chinese market, identify your most commercially valuable claims, and prepare for the slimming strategy I've written about separately. You have until month 30 to decide exactly what claims you need in China. Commission quality translation. A Chinese patent translation done in a rush at month 29 is a liability. A translation reviewed over two to three months, with technical input from your team and legal review from a China Patent Attorney, is an asset. Watch the competitive landscape. PCT applications are published at 18 months from priority. That means by month 18, your application is public. Use the window from month 18 to 30 to monitor what competitors are filing in China — this directly informs whether your claim strategy needs adjustment. Amend under PCT Article 19 or 34. You have specific windows to amend claims and request preliminary examination during the international phase. These amendments can be used strategically to strengthen your position before China national phase entry. A Timeline You Should Pin to Your WallMilestone Deadline Consequence of MissingFile PCT application Month 12 from original filing Lose Paris Convention priorityPCT application published Month 18 Application becomes publicInternational Search Report Typically months 16–22 Evaluate claim viabilityPCT Article 19 amendments Before 16 months from priority Window to amend claims internationallyChina national phase entry Month 30 from priority Lose right to enter (no recovery)One Exception Worth Knowing Design patents (外观设计) in China follow a different, shorter path. The Paris Convention priority window for designs is only 6 months, not 12. If you're protecting a product's appearance — packaging, industrial design, device form factor — that 6-month window applies and moves much faster.Planning your China patent timeline? Our China Patent team manages your PCT timeline from first filing through national phase entry. Or speak directly with a China Patent Attorney about your specific situation.

Practical Answers

By Peter Lin/ On 08 Dec, 2025

Paris Convention vs. PCT in China: A Critical Difference Most Inventors Miss

Last year a Dutch hardware startup came to me eight months after filing their first patent in the Netherlands. They had a working product, a potential distributor in Shenzhen, and a growing sense that they should probably protect something in China. Eight months was still within the Paris Convention window. But when I asked whether they had a finalized Chinese translation of their specification ready to file, the answer was no — and their September launch timeline meant four months were the most they could realistically get. That conversation is where the Paris Convention versus PCT question becomes real. In theory, both routes let you claim your Netherlands filing date as your priority date in China. In practice, only one of them gave this team the time they actually needed. The two main options are the Paris Convention direct route and the PCT route, and in China specifically, there are differences that can significantly affect your cost, timeline, and final patent scope. The Basic Framework Both routes allow you to claim the priority date from your original domestic filing when you eventually file in China. That priority date matters enormously in China's first-to-file system — it determines whether you beat a competitor to protection rights.Paris Convention route: File directly in China within 12 months of your first filing date. PCT route: File an international PCT application (within 12 months of your first filing), then enter China's national phase within 30 months of your priority date.That extra 18 months the PCT route provides is not just a filing convenience. It's a strategic window that most inventors underuse. The Critical Difference Most Miss Here's what I see inventors get wrong again and again: When you file directly into China via the Paris Convention route, you must have a fully translated Chinese application ready within 12 months. That means your specification, claims, and abstract — all in Chinese — submitted together with your filing fee. For an early-stage startup, 12 months from first filing is often not enough time to finalize your design, assess the Chinese market, or arrange quality translation. The PCT route, by contrast, lets you delay that commitment. You file the international PCT application in your own language (typically English), and the Chinese translation only needs to be submitted when you enter the national phase at month 30. That's an additional 18 months to refine your claims, secure funding, or assess whether China is worth the investment. Why China Specifically Amplifies This Gap Many PCT member countries accept English filings even at national phase entry. China does not. CNIPA requires a full Chinese translation of your application at national phase entry. A poor translation can cost you claim scope — permanently. Under Chinese patent practice, if there is a discrepancy between the original PCT application and the Chinese translation, CNIPA will generally rely on the Chinese translation as the basis for examination. This makes translation quality a strategic issue, not just a clerical one. The extra time the PCT route provides lets you commission and review a professional-grade translation — rather than rushing one through in the final weeks before a 12-month Paris Convention deadline. The Trap: Assuming PCT Is Always Better PCT is not universally superior. Here's when the Paris Convention direct route makes more sense for China Patent filings:You are confident about the Chinese market now. If you have a distribution partner, manufacturing arrangement, or real commercial activity in China within 12 months, you may not need the extra time. Your technology is simple and the application is short. Translation cost and risk are proportional to specification length. A 10-page utility application translates much faster and more reliably than a 100-page biotech filing. You want to avoid PCT fees. PCT filing has its own international fee structure. If you're early-stage and China is your only international target, the direct route may be cheaper overall.What a China Patent Attorney Will Actually Tell You When I advise clients as a China Patent Attorney, this is the question I always ask first: How confident are you today about what your Chinese patent needs to protect? If the answer is "very confident, and we have a product ready to launch," the Paris Convention route is often fine. If the answer is "we think China matters but we're still refining the product," the PCT route is almost always the right choice — not for the extra protection it adds, but for the strategic flexibility it buys. A Simple Decision FrameworkSituation Recommended RouteProduct is final, China launch within 12 months Paris Convention directStill refining design or claims PCT → China national phaseMultiple countries beyond China PCT (efficiency of one filing)Budget-constrained, China only Paris Convention (lower upfront cost)Complex specification, translation risk PCT (more time for quality translation)Have questions about your China patent filing strategy? Explore our China Patent services or speak with a China Patent Attorney about whether Paris Convention or PCT is the right route for your situation.